The opportunity and challenge for the OCTG manufacturers going out

Opportunity and challenge

In recent years, the international exploitation and transportation of oil and gas is in the peak, the market potential is huge, which provides a rare market opportunity opportunity for China's oilfield pipes and supply. At the same time, due to the complexity of the global political and economic situation, it also brings the risks and challenges for octg manufacturers “going out”.
As a new force in oil pipeline supply, TICO oiltubulars expand the international market actively in recent years, achieving remarkable achievements and exploring a lot of successful experience for the oil pipeline enterprises "going out".

The international political and economic instability become the biggest challenge for octg manufacturers going out

In the process of economic globalization, more and more octg manufacturers follow the trend of "go out" to participate in the international market competition. However, compared with the domestic market, the international market is broader, the competition is more intense and the risks and challenges are more prominent. Generally speaking, the international octg market is facing the challenge of political risk, financial risk, market risk, exchange rate risk, legal risk, safety and environmental risks, labor risk, cultural practices and so on.
After the international financial crisis, the economic pattern of the world is in a major adjustment, the commodity price shock upstream, the European debt crisis intensifies, dollar currency rate continues to decline. Especially the world economic recovery is slowing and the growth of international trade is dropping. Overall, there are more and more uncertain factors in oilfield pipes, so the business risk is growing.
In addition, competitions among the octg manufacturers are becoming increasingly fierce with engineering profits shrink and the market risk increases. With the impact of the world financial crisis continues to spread and the degree of global economic integration is deepening, fierce competition in oilfield pipes is caused among countries, which increases the difficulty to develop the octg market.

Strengthen risk management and control to enhance the ability to respond

With the increasing competition in the octg industry, the pipeline engineering construction has more and more challenges, so the effective control of risk becomes the inevitable choice for octg manufacturers.
In the process of "going out", our company follow the principle of "safety, effective, sustainable" , pay attention to establish risk precaution system, constantly enhance the ability to resist and defuse the risks. In order to effectively prevent and control the risk of security, reduce cost of enterprises, our company promotes international business localized and regulates the localization project management.

Conclusion

It thus appears that facing opportunities and challenges of octg industry, our manufacturers need to recognize the reality to seize the opportunity, adjust the strategy actively, adhere to the policy of "going out", and enhance the competitiveness to open oilfield market.

What is OCTG and global OCTG market outlook

What is the meaning of OCTG?

For the oil and gas industry exploration and production activities, Oil country tubular goods (OCTG) are hollow steel products, which is circular cross-section. OCTG can be produced as seamless or welded tubes and pipes. As the capital investment to manufacture seamless OCTG is ten to twenty times higher than the investment required to manufacture welded OCTG, so appropriate selection of OCTG can reduce the risk of great opportunities to minimize risk, and save cost.

Due to high exploration and production activities, growth in the proven shale reserves and escalating investments from the oil and gas operators, the demand of OCTG is higher and higher. This trend will continue to rise because of the current surge in offshore activities and shale reserve exploratory activities. The global OCTG market is thereby expected to grow to approximately $59 billion by 2019 and the growth rate of CAGR will exceed 7% from 2014 to 2019.
The OCTG market is divided into six regions, namely North America, South America, Europe, Africa, Asia-Pacific, and the Middle East. According to major countries in the region, the OCTG market can be further subdivided. Geographically, Asia-Pacific and North America are the largest markets which have grown rapidly in the past decade. In Asia-Pacific, China is the largest market which will continue to dominate the OCTG industry. North America follows the Asia-Pacific market with U.S, being the most influential player due to activities in abundant shale reserves. These regions are likely to continue to dominate in the future. The South-American market will witness the highest growth rate; Europe and Africa will also develop with a decent CAGR.

Outlook of OCTG market

The key factors driving the OCTG market is the increasing global demand for oil and gas, growth in crude oil prices, economic growth and lack of alternative sources of energy. Some noteworthy development of this industry include global rig count growth, increasing global E&P spending, and the seamless pipe industry, among others.

Oil country tubular goods are essential in the mining period of the oil and gas.

Globally, with the increasing exploration and production activities and the new unconventional resource area have become the main driving force for the growth of OCTG market. As competition continues to intensify, more and more companies are beginning to pay more attention to environmental safety. So the market will witness the high growth rate of premium product type such as OCTG.
These factors contribute to the growth and development of OCTG products:

• Over the past years, bourgeoisie population and globalization develop vigorously, which is the reason why oil, gas and energy demand is growing faster than expected.
• Technological innovation and rapid economic expansion are a number of other important factors in developing country, which has been guiding the needs of energy.
• The increase of investment and exploration in oil and gas further promotes the oil and gas industry.

How to distinguish hot and cold seamless pipe?

A large number of seamless steel pipes are used for conveying fluid because of a hollow section, such as crude oil, nature gas or water. Under the same torsional strength, seamless steel tube is relatively light comparing with round steel or other solid steel. It’s an economical steel which is widely used in manufacture oil pipe and mechanical parts, such as drill pipes, automobile transmission shaft or steel ring parts.The reason why seamless pipe used widely is it can improve the utilization of materials, simplify the manufacturing process and save materials and processing time.
Seamless steel tubes are made by hot rolling or cold rolling with 10,20,30,35,45 high quality carbon steel and 16Mn, 5MnV low alloy structural steel or 30CrMnSi, 40Cr, 45Mn2, 40MnB alloy steel. Seamless pipe, made by 10,20 and other low carbon steel production, is mainly used for conveying pipe, while made by 45,40Cr medium carbon steel to manufacture mechanical parts.
The production process of seamless steel tube in general can be divided into hot rolling and cold rolling. 

Cold rolling seamless steel pipe

The production process of cold-rolled seamless steel pipe is generally more complicated than that of hot-rolled: tube is first to three roller skew rolling, then, to carry out a sizing test after extrusion. Round tube needs to cut through cutting machine and the length is about 1 meter. Entering the annealing process, annealing carry out pickling should pay attention to whether the surface has a large number of foaming, if there is a large number of bubbles produced that the quality of the steel pipe is not up to the corresponding standard. Cold-rolled seamless steel pipe is shorter than the hot rolled seamless steel pipe in appearance, but the surface looks brighter than the thick walled seamless steel tube.

• Advantage

  Forming fast, high yield, and no damage to the coating, it can be made into a variety of cross sectional form to meet the needs of the use of conditions; Cold rolling can cause great plastic deformation, so as to improve the yield of the steel.
  

• The technological process of cold-rolled seamless pipe

  round billet→heating→perforation→annealing→pickling→annoit→cold rolling→heating→straightening→hydrostatic test→signing→storage
  

Hot rolling seamless steel pipe

Hot rolling, as the name suggests, the temperature of rolled piece is high, so the deformation resistance is small to achieve large deformation. Take rolling of steel plate for example, the general thickness of continuous casting slab is about 230mm, and after roughing mill and finishing mill, the final thickness is 1~20mm. At the same time, due to the small thickness ratio of steel plate, the dimension accuracy is relatively low, it’s not easy to cause shape problem.

• Advantage

  It can destroy the microstructure of ingot casting, grain refinement of steel and eliminate microstructure defects, so that make steel structure compact and improve the mechanical properties. This improvement is mainly reflected in the rolling direction, so that the steel no longer is isotropic; Formation of bubbles, cracks and loose when pouring can also be welded under high temperature and pressure.
  

• The technological process of hot-rolled seamless pipe

  round billet→heating→perforation→extrusion→sizing→hot rolling→cooling→straightening→hydrostatic test→signing→storage
  

What are delivery status of steel

Steel used in the oil tubular goods will pass through a complex process before leaving factory. According to the different characteristics and use of steel, the final delivery state of the steel is different. Common delivery conditions are: hot rolling treatment, cold stretching treatment, normalizing treatment, annealing state, high tempering state and solid treatment.

Hot rolling treatment

It’s known as hot rolling treatment when steel deliver directly after cooling without special heat treatment. The terminal temperature of hot rolling treatment is between 800℃ and 900℃, after that, it’s generally refrigerated in the air. As a result, the hot rolling treatment is similar to normalizing treatment. The difference is due to the hot rolling termination temperature fluctuated, which is different from strict normalizing temperature, fluctuations in steel microstructure and properties are more than that of normalizing treatment.

Currently, many steel companies apply controlled hot rolling. Because of strict termination temperature and forced cooling measures, delivered steel has higher comprehensive mechanical properties. Covered with a layer of iron oxide, delivered steel with hot rolling treatment has a certain degree of corrosion resistance. The storage requirements of hot rolling steel are unlike to cold stretching, medium-sized steel and thick steel plate can be stored in the open air yard.

Cold stretching treatment

The steel by cold stretching, which is without any heat treatment and direct delivery, is called cold stretching treatment. Compared with hot rolling treatment, cold stretching treatment steel has the features of good surface quality, low surface roughness and higher mechanical properties. However, the surface of steel staying cold-drawn state is not covered with oxide skin and there is internal stress result in corrosion and rusty. What’s more, the packaging and storage of that has higher strict requirements, that it’s generally stored in the warehouse and the temperature and humidity in warehouse should be controlled.

Normalizing treatment

Through normalizing before leaving factory, the steel is staying normalizing treatment. Since the normalizing heating temperature is stricter than hot rolling terminated temperature, the performance and organization of steel has stable performance. Compared with steel annealed condition, because of faster speed of normalizing cooling, pearlite in the steel is increasing and lamellar, therefore it has a higher comprehensive cooperation properties and it’s profitable to improve Widmanstaten of low carbon steel and make preparation for further heat treatment.
normalizing treatment

OCTG industry meet the opportunity because of the belt and road

What is "The Belt and Road"

Starting Central Asia and through South Asia, Southeast Asia, West Asia, Eastern Europe, "The Belt and Road" has been a longest world’s economic corridors. It is becoming the most development potential economic belt in the world. What’s more, countries along the fate become more and more close whether in the eyes of the economic development and improving people's livelihood or from the point of response to the financial crisis.


Currently, China is the world's largest energy consuming country and the second oil and gas consumption country. With the development of “The Belt and Road”, China will become the main resource exporting country.

A new opportunity to OCTG industry

In fact, countries alone “The Belt and Road” have a wealth of crude oil resources, but their infrastructure is relatively weak, which create a huge opportunity for China's OCTG industry. As we all know, influenced by the international market, not only steel pipes but also other export goods made in China were known as cheap in the past decades. We offer high-quality pipe with the lowest price. In other words, It’s a best time to buy cheap steel pipes from China if you need. "The Belt and Road" will help us develop new export markets, solve the dilemma of overcapacity and this will promote the economic and trade exchanges between China and the neighboring countries.

Some countries in Southeast Asia and South Asia develop slowly and have a large population, but the development of “The Belt and Road "must rely on the railway, highway, pipeline, shipping routes. Therefore, transportation, energy pipe network, manufacturing facilities, raw materials and equipment, high-end equipment, energy saving and environmental protection industry will usher a great opportunity. In the oil and gas industry, for example, with the completion of natural gas pipeline between China and Myanmar, a series of OCTG products in South Asia, Southeast Asia will have a good market prospects.


According to statistics in 2015, Chinese enterprises invest in 49 countries related to "The Belt and Road" directly and the investment grew 18.2%. Insiders have said that, under the stimulus of "The Belt and Road" policy, the next few years, the chemical industry is expected to recover.

CIPPE----an annual event in petrochemical industry

In petrochemical industry, there is an annual event, the Eighth China International Petrochemical Technology and Equipment Exhibition (CIPPE Shanghai Petrochemical Exhibition) will be held in Shanghai New International Expo Center on August 23-25. After eight years of development, CIPPE has developed into a communication and learning platform for trade cooperation, which is regarded as one of the highest quality in the petrochemical industry on businesses and professionals. Many companies will be unveiled this collective exhibition, to discuss "The Belt and Road" strategy for promote the petrochemical industry. We welcome you to attend and have a pleasant communication.

Present Situation And Development Of Oil Pipeline System

Composition of oil pipeline system

Long distance oil pipeline consists of two main parts: the oil transportation station and the pipeline.

oil transportation station

The starting point of the pipeline is an oil transportation station, known as "the first station", after the crude oil is collected and calculated, the first station provides power to transport to the downstream pipeline. The first station is generally arranged with oil storage tanks, oil pump and oil metering device. Oil pumps provide power to make the oil moved along the pipeline to the terminal or the next level of oil transportation station. Under normal circumstances, due to the long distance, the energy loss of transporting process is obvious, it’s need multilevel oil stations to provide power until crude oil sent to terminal. The end of the oil station known as "terminal station", mainly responsible for collecting material transported from the upstream pipeline, therefore equipped with many tanks and metering system.

Pipeline

Long distance oil pipeline is welded by steel pipe. An insulating layer is wrapped outside the tube to prevent corrosion of the chemical composition in the soil. The internal pipeline can be also coated with anti corrosive material to reduce the corrosion in the transmission of oil and improve the smoothness of the pipeline for large transportation quantity. Every certain distance or across a large obstacle, the pipeline is equipped with a valve to prevent the expansion of the accident and convenient to maintain equipment.

Development Direction

Normal temperature transportation technology

With the increase of the oil production and the exploitation of crude oil to the deep sea, all countries attach great importance to the research on the transportation and flow security technology of waxy oil.

Pipeline monitoring technology

Early warning technology, divided into field type monitoring and sensing monitoring, is becoming a developed pipeline monitoring technology in twenty-first Century. Field type monitoring focus on monitoring people's entry can only be used for a short period of time. Sensing monitoring focus on monitoring can be used for long distance and long time monitoring. These monitoring are affected by various factors, so that they has been subjected by a variety of technical limitations in application. It shows that these monitoring methods need further research.

Some Issues About OCTG Casing And Its Transportation

The classification and function of casing

OCTG casing is a steel pipe supporting oil and gas well wall, which ensures the normal operation of the entire well after the drilling process carried out. Different from tubing and drill pipe, casing can not be repeated use and belongs to a one-time consumption of materials. Therefore, the consumption of the casing pipe accounted for more than 70% of all. According to the situation of use, casing can be divided into: tube, surface casing, technical casing and oil layer casing.

Connection type of casing

Short round thread casing connection type

The short round thread casing is one of the product types in the petroleum casing pipe. Short round thread casing features: 1. Improve resistance caused by abrasion when the thread in the screw. 2. When tightening screw, tooth gap provides a reasonable gap for foreign particles and dirt. 3.The arc tooth top is not sensitive for local scratch or dent damage.

Long round thread casing connection type

Long round thread casing is widely used as a buckle-shaped of oil casing. Due to the thread shape at both ends of the pipe body is like long round, so it’s called long round thread casing. Long round thread has the advantages of easy processing, good sealing performance, strong connection strength and cheap, so it’s widely used in the casing connection.

Buttress thread casing connection type

Buttress thread casing have the name because the thread form is like partial trapezoidal and this thread is widely used in all the thread. The packing of the buttress thread casing is tied up with the steel wire or the steel band. The advantages of this thread improve axial tension and axial compression load and the leakage resistance is also provided.

Casing transporting

• Casing before loading and unloading, the inner and outer screw threads must be tightened by special tools.
• The casing should be hoisted with nylon rope.
• The pipe rack car or wagon should pad sleeper which cross section is 150mm×50mm. If the shipment is more than two layer, the sleeper shall be 300mm×60mm.
• When casing loading, external thread or coupling should be installed one end of vehicles.
• Casing vehicle is strictly prohibited overload, over high.
• You should stop in time to prevent casing loosening and ensure safe transportation in transit.
• Casing should be unloaded from the building root in turn. Control casing running speed, avoiding hit front casing when landing.
• The number of loading casing can not more than 10 roots when using forklift and do it gently to avoid collision.

Coiled tubing, current advanced operation technology in OCTG tubing

OCTG tubing is a pipeline which transports crude oil and nature gas from hydrocarbon reservoir to the surface after the completion of drilling. It’s one of the main products of OCTG and it can withstand the pressure generated in the process of mining. While Coiled tubing technology is the current international advanced operation technology. Coiled tubing is made of low carbon alloy steel pipe and has good flexibility. A roll of coiled tubing is thousands of meters long, which can be used to replace conventional tubing for a lot of work. Coiled tubing operation equipment has the characteristics of pressure operation and continuous up and down.

History of coiled tubing

In 1962, the United States California oil companies and Bowen Oil Tools Company jointly developed the first coiled tubing light workover device. The coiled tubing diameter was 33.4 mm, which  mainly used for sand flushing operation of oil and gas wells in the Gulf of Mexico. 30 years after the birth of the coiled tubing, its value was really understood, to the 1990s, coiled tubing technology has been the development by leaps and bounds. Coiled tubing device has been known as the "universal operating machine", widely used in the oil and gas well workover, drilling, completion, well logging throughout the whole process of the exploitation of oil and gas.

 

The development of the number of coiled tubing equipment is as follows: 1962, the first coiled tubing equipment was born; in the mid-1970s, approximately more than 200; in 1993, about 561; at the beginning of 2001, about 850; at the beginning of 2004, about 1050 units, mainly distributed in North America, South America and Europe; At the beginning of 2011, about 1881, China has 61.

API standard and product specification level(PSL) for pipeline

API standard for pipeline

Line pipe is a dedicated pipe which can transport oil, steam or water to oil and gas industry enterprises. Pipeline includes seamless and welded steel pipe which the ends are flat end, threaded end and the socket end. The connection mode is welding, connection, socket connection and so on.

API is known to everyone in the steel industry and it has long been inscribed in the hearts of every person in the steel tube. API refers to the American Petroleum Institute, while API 5L is the production execution standard of pipe line.

API 5L pipe production is currently using micro alloy heating treatment process. The production costs of seamless stainless steel pipe are significantly higher than the welding pipe and with the increase of steel grade, the limit of carbon content is more and more strict. At present, all the major manufacturers carry out research work in order to improve the corrosion resistance of the pipeline and ensure the stable performance in low and high temperature.

PSL product specification level

PSL is referred to as the level of product specification. The product specification of the pipeline is divided into PSL1 and PSL2, there is a difference of only a single word, but the content of these two standards are completely different. The quality level of PSL2 is higher than that of PSL1, these two standards are not only different from the inspection requirements, but also the chemical composition and mechanical properties are different.

Why Need Post Weld Heat Treatment(PWHT)?

Due to the steel pipe transporting gas or liquid need to bear a certain pressure, internal stress produced in the cold rolling process must be eliminated. Welding process, because local overheating will cause the pipe deformation and shrinkage stress, so steel pipe return to heat treatment after welding to eliminate internal stress.

PWHT is based on the hardness of the steel, the thickness of the welding parts, structural rigidity, welding methods and conditions of use. General carbon steel welding performance is good, the welding can be without preheated and heat treatment. But for the high carbon content and high stiffness of the welding parts, it is required to preheat and heat treatment, such as the wall thickness of 30mm carbon steel pipe.

Method of PWHT

The method of PWHT is electric heating. The caterpillar electric heater and linear electric heater should be fixed on the parts which are needed to PWHT; they connect with the automatic controller through cable. And the thermocouple should be fixed on the parts needed to PWHT through the compensating conductor. It connects with the computer automatic controller. Then the controller will work automatically according to the process parameter that is being inputted into the controller.

General rules for PWHT

• On the stress corrosion of the weld, should be carried out post weld heat treatment.

• Prone to delayed crack in steel welding, it should be timely carried out heat treatment after welding. When the heat treatment is not timely, it should be heated to 200℃~300℃ immediately after welding, and the heat preservation and slow cooling, the heating range should be the same as the PWHT.

• After welding heat treatment and before the pressure test, appearance inspection and non-destructive testing should be carried out.

• PWHT qualified parts, should not engage in welding operations, otherwise it should be re-heat treatment.

• Welding inspector should be professional trained and welding heat treatment personnel should be in accordance with the norms and welding work instructions to handle heat treatment.

• When heat treatment is carried out, the temperature should be measured and recorded, the position and quantity of the temperature measuring point should be reasonable, and the temperature measuring instrument should be qualified and effective.

How To Carry Out Pipe End Machining

What is pipe end machining

Pipe end machining is that the process of pipe thread, sizing, thickening, strengthen the heat treatment, chamfering and other processes are carried out on the end of pipe. Each process is quite important for carrying out the pipe end machining, let's look at all the processes together.

Pipe end thickening

Pipe end thickening is mainly used for the oil pipe and geological tube. Since the pipe wall will be thinned after the end of processing, the part of threaded connection has become the weak link of the whole pipe body. In order to improve the strength of the connecting part of the thread, the method of pipe end thickening is adopted to increase the wall thickness of the pipe end. There are 3 forms of pipe end upsetting, internal upsetting, external upsetting, internal and external upset.
The process of pipe end thickening is:
pipe end heated→thickened→cooled→checked.
According to the size of the thickened tube, the thickness of the form and the amount of thickening of the compression, the number of heating and thickening is not the same, there is one heating one thickening, or two thickening one heating. In order to eliminate the phenomenon of uneven performance of the thickened end and the pipe body caused by the thickening, the steel pipe usually does integral heat treatment after thickening.

API steel grades for tubing and casing

API standards for Casing and Tubing

API, shorted for American Petroleum Institute, is considered as one of the most authoritative and comprehensive principles for oil and gas industry. Products complied with API standards are always thought of reliable quality. Under the general standards, there are some subordinated specifications drafted for each specific OCTG product, such as API 5B, API 5CT, API 5D, API 5L and so on.

API 5B and 5CT are mainly used for tubing and casing, standardizing the chemical properties, steel grades, manufacturing methods, color coding, heat treatment, inspection, etc. Tubing and casing are supposed to withstand specific pressure in transportation of oil or natural gas, which means the steel material should have proper yield strength, therefore API 5B and 5CT lay specific standards of steel grade for tubing and casing to meet the general application purpose.

Color codes for API steel grade

In order to clearly distinguish the steel grade, tubing, casing and its coupling should be painted with color codes respectively. Color bands should be painted on tubing and casing body longer than 600mm to either end. The whole outer-body of the coupling needs to be painted color and then color codes.

API 5B and 5CT provide various steel grades and color codes of each grade, offering detailed and overall information of casing and tubing, which help you clearly pick out the most suitable products for different well application.

learn more...

Quality Inspection Of Seamless Steel Pipe

Seamless steel pipe is one of the important products in OCTG products. It is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automobile transmission shaft, bicycle frame and construction of steel scaffolding and so on. Comparing with the other steel pipe, seamless steel pipe has stronger anti-bending and torsional ability under the condition of the same cross section area. It is widely used in the national economy, and is entitled to the "industrial blood vessel". Therefore, the quality of seamless steel pipe has very demanding requirements.

Seamless steel pipe inspection generally include: inspection geometry, surface quality; test chemical composition, mechanical properties, process performance, high and low times of the organization; NDT inspection; some special performance inspection and weighing length measurement. Let’s look at some relatively important quality inspection together.

 

Seamless steel tube geometry inspection

• Seamless steel pipe wall thickness inspection    Micrometer is the main tool that is adopted. When you check, left hand holds the micrometer stand, with right hand rotation induced wheel, and the wire rod should be coincident with the diameter of the measuring point. Once found that the wall thickness is not qualified, it should be marked in time.
• Outside diameter, ellipse of seamless steel pipe inspection    Calipers, vernier caliper should be taken. The caliper should be perpendicular to the axis of the steel pipe in checking, measuring the maximum and the minimum point when the pipe rotated slowly. Founding the outer diameter of large or small, you should mark it in time.
• Seamless steel tube length inspection    The steel tape can be measured directly by metallic tape.
• Bending inspection of seamless steel tubes    With the tools of level, feeler and line.
• End profile inspection    At two ends of the steel tube should be cut into specified angle and remove burrs. The method of inspection adopts angle square and general use tube end groove clamp in the field.

Mechanical properties and process performance check of seamless steel tube

In order to verify the mechanical properties of seamless steel pipe to meet the requirements of the standard, the test sample of seamless steel pipe mechanical performance should be prepared carefully. Mechanical property test includes tensile strength, yield strength, elongation, impact energy and so on. Process performance test includes flattening test, flaring test, hydrostatic testing, curling trials, cold bend test, perforation test. These test items are based on different standards and different uses of seamless steel tubes.

Non-destructive testing of seamless steel pipe

Under the premise of not damaging the specimen, NDT refers to carry out inspection and testing to internal and surface structure, properties, status of specimen with physical or chemical methods, advanced technology and equipment. The development of non destructive testing technology has experienced three stages: Nondestructive detection, nondestructive testing and nondestructive evaluation.

Nondestructive detection is the name of the early stage, and the meaning is to detect and detect defects; Nondestructive testing is the name of the current stage, its meaning is not only to detect defects, but also to detect some other information, such as the structure, nature, status, etc.; And nondestructive evaluation (NDE) is one which is entered or is entering a new stage, it requires not only the defects are found, but also detection test pieces of the structure, properties, status, and access more comprehensive and more accurate, comprehensive information, such as defects associated with the shape, size, location, orientation, inclusions, tissue defect, residual stress force of information. It is necessary to combined with imaging technology, automation technology, and computer data analysis and processing technology, and mechanics of materials, and other fields of knowledge, and gives a comprehensive and accurate evaluation of the quality and performance of the test piece or product.

Pipeline welded joint design

In practical industrial application, line pipes are always welded to join together to form longer ones to meet the needs of engineering project. The welding joint is supposed to be as strong as the base material, not subjecting to fatigue, bending, crack or other defects.
The most commonly-used type of pipeline joint is butt joint, a process in which two pieces of pipes are joined together in the same horizontal plane. Butt welding has the advantage of good tolerance, high strength and less needed material. However, butt welding doesn’t mean the simple face-to-face connection of two pieces, which means the joining surface are not always vertical to the pipe plate. The edges of pipes are processed into different angles before welded, that’s what called pipeline beveling.

What is pipeline beveled end and why use it

Beveled end, to put it simply, is a joint surface with a specific beveled angle. In fact, it is processed prior to the welding of two pieces of line pipes, an angle formed at the edge of the end of the pipe with the help of a beveling machine.
Its foremost use is to achieve the best butt welding joint. Some pipes, especially those with great wall thickness, are difficult to be welded together due to low penetration. Even if joined together, they may not be deeply and completely welded due to the great thickness, so potential welding defect remains. Thus, when both ends of the pipes are beveled to form an angle, the thinner walls make it easier for pipes to be jointed together. Some filler materials will be put in the beveled space. The bevels increase their contact area, guaranteeing a better and deeper welding effect. Besides, pipeline beveling can be used to deburr the cut ends, making the pipes neat and tidy.

Common types of beveled ends and comparison among different types

Beveling ends can be made into various angles, achieving the better welding seam. Common beveled ends for butt joints are I-Type butt joint, single-V beveled end, double-V beveled end and single U-beveled end.
Beveled angle refers to the angle between the two beveled surfaces. Beveled face angle, normally used for single-U type, refers to the angle between the beveled surface and the vertical line to the pipe itself. The root opening refers to the gap between the roots of both pieces before welding, to ensure the roots get complete welding. The root radius for single-U beveled end is to increase the transverse space between the roots, making the welding reach the bottom of the root.

• I—type butt joint, also called square butt joint, is a relatively simple joint method for pipes of 1 to 6 mm in thickness. Strictly speaking, it is not a beveled end joint, for it only requires parallel matching the edges of two pieces together without certain angles. It is easy and economic to process, but is not recommended for pipes of thick walls.  As for thicker wall pipes, the angle of the bevel ends needs full consideration, trying to use the least filler metal material to provide the desired welding soundness.
• Single-V beveled end, is the most widely-used butt joint type in pipeline application. It suits pipes with the thickness of 3 to 26 mm. The beveled angle should be approximately 40 to 60°. Single—V beveled end is processed by a beveling machine. Comparatively speaking, it is more costly and needs more filler material than the I—type butt joint, but the joint is much stronger than the square joint. The disadvantage of single-V beveled end is its easy subjection to angular deformation.
• Double-V beveled end, also called X—beveled end, is developed on the basis of single—V beveled end. It needs double-side welding, so the material needs to be turned over after welded one side and the preparation time is longer than the single-V beveled end. It can be used for pipes of thickness 12 to 60mm. For pipes of same thickness, a double—V beveled end requires less filler metal material, because there are two narrower V-joints compared to one wider single—V beveled end.
• Single-U beveled end is a one-side welding joint. It requires less filler metal material than double—V beveled end and is less subjective to deformation. However, due to the radian shape, it is more difficult to process than the former methods.

Anson provides you pipelines with beveled ends

Different types of beveled ends have different requirements on pipes and welding methods. As a professional pipeline supplier,
Tianjin Anson International Co., Ltd provides beveling service according to your requirement. Clients can choose pipes with the most suitable beveled ends before welding application to achieve better pipeline butt welding performance.

What Are The Important Steps In The Oil Pipe Processing

Pipeline straightening

Generally, pipeline has to go through a number of long-distance or short distance transport, and finally arrived at the use of the site. In the course of transportation and loading, the collision or breaking of the pipe is difficult to avoid. Therefore, in order to make the pipeline construction to meet the acceptance criteria, it is necessary to straighten the pipe. Generally, for manual straightening, the diameter of pipe is smaller than by machine which pipe is straightened with a diameter larger than 50mm , sometimes pipes need to be heated before straightening under special circumstances. When the pipe diameter is larger than 200mm is generally not easy to bend or deform, therefore rarely need pipeline straightening.

Welding

Welding is a main form of pipe connection. There are many kinds of welding methods, commonly used in gas welding, arc welding, argon arc welding, argon itu welding and carbon dioxide welding. Checking whether the tube incision and groove to meet the quality requirements before pipeline welding. Then when nozzle paired, the inner wall should be flushed. Specified requirements, the general pipeline should not be more than 10% of the thickness of the wall, and not more than 2mm; Grade SHA piping should not be more than 10% of the thickness, and not more than 0.5mm.

Groove processing

Groove processing is an effective measure in order to ensure the quality of pipe welding. There are various forms of groove, the selection of groove type should consider the following aspects: 1.ensure the welding quality 2. welding operation is convenient 3. save electrode 4. prevent pipe deformation after welding.

There are several groove types often used in pipeline welding, I-groove, V-groove and U-groove. I-groove applies to welding nozzle which pipe wall thickness below 3.5mm. According to the situation of the thickness, adjust nozzle clearance to ensure weld penetration. This kind of weld, pipe wall without chamfering, actually is no need for processing groove, as long as the verticality of pipe incision can guarantee the requirements, you can direct welding. V-groove is applicable to low pressure pipe welding. The groove of angle is from 60 degrees to 70 degrees and the root has a blunt edge which height is 1 ~ 2mm. U-groove is suitable for high pressure pipe welding. The thickness of pipe wall is between 20mm and 60mm and the root has a blunt edge which thickness is about 2mm.

The form and size of groove processing should be consistent with the specified in the design document. Pipe groove processing should adopt mechanical method, plasma arc and other heat processing method can also be used. After a heat processing method, should remove the oxide skin on groove surface, slag and irregularities should be polished smooth.

Pipe cutting

The purpose of pipe cutting is to cut a section of the pipe with a size requirement. According to the requirements of the specification, different materials of the pipe should be used in different cutting methods. Carbon steel pipe, alloy steel pipe shall be cut by mechanical method. When using oxygen acetylene flame cutting, we must ensure that the correct size and smooth surface. Stainless steel pipe, non-ferrous metal pipe should be used in mechanical or plasma cutting method. Galvanized steel pipe should be with a hacksaw or mechanical cutting. Pipe cutting is an important working procedure, the quality of pipe cut has a direct impact on the next operation incision.

Pipe, pipe fittings cleaning inspection

The pipe should be cleaned and checked before installation. The dirt and impurities should be removed, and the appearance inspection should be carried out according to the current regulations of the country, and the unqualified shall not be used. The inspection of the pipe mainly has the following several points:

• Check the specifications, quantities and marks of the pipe according to the design requirements.
• If the objection to the quality of the book is not resolved, the batch of pipes shall not be used.
• Whether the pipe has cracks, shrinkage, slag, folding, heavy leather and other defects.
• Thread sealing surface, the machining precision and the roughness of the groove should meet the design requirements and manufacturing standards.
• In grade SHA piping, the outer surface of the pipe with the design pressure equal to or greater than 10MPa shall be carried out in accordance with the provisions of the non-destructive testing.

Different Kinds Of Oil Casing Test

Oil casing pipe is a high end product of steel pipe production. There are many kinds of casing, the diameter of the casing is in the range of 15 kinds of specifications and the external diameter of casing is 114.3-508mm. Steel grade is divided into J55, K55, N80, L-80, P-110, C-90, C-95, T-95 and so on; There are different kinds of type and requirements of the casing pipe end button type, the processing button type has STC, LC, BC, VAM and so on. There are many tests in the production and installation of the oil casing, including the following aspects:

Ultrasonic Testing

When the ultrasonic propagates in the detected material, acoustic characteristics of materials and internal organizational changes have a certain effect on ultrasonic propagation. By detecting the extent of ultrasonic affected, to understand the changes in the performance and structure of the material.Radiographic Testing

The amount of radiation from the normal part and the defect is different, according to this, ray detectors can cause differences in the blackness of the negative.

Penetrant Testing

Take advantage of capillary action, penetrant testing will penetrate liquid into the opening on the surface of solid materials, and then imaging agent suction the liquid to reveal surface defects. From the penetration operation to the defect display is relatively short, generally about half an hour, you can test surface fatigue, stress corrosion and welding crack, the size of the crack also can be directly measured.

Magnetic Particle Testing

The magnetic flux leakage of the casing tube defects can adsorb the magnetic particle forming the magnetic mark, so as to provide the defect display. Magnetic particle testing can test the surface and subsurface defects, the defect is easy to identify. Paint and plating surface does not affect the detection sensitivity.

Eddy Current Testing

Take advantage of eddy currents induced by ferromagnetic coil in the workpiece, the quality of the internal workpiece is analyzed. Eddy current testing can test the surface defects of various conductive materials, and can indirectly measure the length of the defect, but it is difficult to control the parameters, and the results are difficult to interpret. What’s more, the object to be detected must be conductive crack.

Magnetic Flux Leakage Testing

The magnetic flux leakage detection is based on the characteristics of high permeability of ferromagnetic materials. Measuring permeability changes due to defects in ferromagnetic materials to test the quality of in-service oil casing.

Magnetic Memory Test

Magnetic memory testing is the relationship between the physical nature of the magnetic phenomenon and the process of dislocation, which has high efficiency, low cost, no need to be polished and so on. It has important and wide application prospects in industry.

Development of magnetic memory testing technology

As we all know, ferromagnetic metal materials as a force structure can withstand fatigue loads in different degrees, so as to cause fatigue crack.

Due to fatigue crack mostly sprouted in the stress concentration region caused by surface defects, adding the stress concentration in the component can cause the material to produce the early damage such as stress corrosion, therefore, it is very important to effectively carry out the test of the surface stress of the component. Because some of the components must be loaded and some of the equipment is complex in the conventional stress testing methods, most of them are not adapted to the non-destructive testing of industrial field.

In 1990s, Russian scholars first proposed that the stress concentration zone of the component surface can be detected by magnetic memory. The magnetic memory testing technology is expected to accurately test the dangerous parts that are characterized by stress concentration. This is a new nondestructive testing method for the early diagnosis of metal components, thus the theory has been paid attention by all the countries in the world.

It is anticipated that, as a new in-service diagnostic methods, magnetic memory testing technology will be further developed through non-destructive testing industry colleagues tireless efforts, for the benefit of human society.

Conclusion

In these tests, there is no specific standard for the magnetic memory testing, yet to be developed. The remaining six kinds have their own testing standards and more mature.

Summary For Casing And Tubing Failure Modes

Casing and tubing is an important material and equipment in the petroleum industry and it has a great amount of use. Casing pipe and pipe string failure will lead to the entire pipe string can not work normally and you will see a lot of casing and tubing corrosion in the construction site. Based on this, the applicability evaluation of casing and tubing with suspected defects is proposed, not only you can make a judgment on the quality of the tubing, but also you can regulate the tubing which doesn’t meet the standards.

The working condition of casing and tubing is relatively poor, and the stress state is complex, so the failure mode is varied, and the failure analysis is summed up in the following 3 types:

Deformation failure

In practical applications, due to the radius of casing and tubing is much smaller than that of the license, instantaneous plastic bending deformation is usually occurred in casing and tubing. It will cause permanent bending of casing and tubing (commonly known as dead bending) in a long time.

In addition, flexible deformation beyond the tensile limit, exceeding the limit of deflated or compressed phenomenon are all part of the deformation failure.

Fracture failure

Fracture failure in the casing and tubing is a large proportion of failure fracture, especially the fatigue fracture that damage is more serious. The main fracture forms are:

• Overload fracture   The speed of pipeline into the wells is too fast, resulting in its snap off when encountered downhole plug or during the job the underground fallen objects lead to pull off and so on.
• Low stress brittle fracture   Brittle fracture of the casing and tubing weld.
• Stress corrosion fracture   Sulfide stress corrosion cracking can be caused when working in oil and gas wells with high sulfur content. The characteristics of the stress corrosion fracture usually have 3 areas, fault source area, crack propagation region, fast break or tearing zone.
• Hydrogen embrittlement   When the tubing material contains too much hydrogen, it’s easy to produce hydrogen embrittlement in tensile force. The characteristics of hydrogen embrittlement fracture are in the fracture edge can be observed in white or white light ring.
• Fatigue fracture and corrosion fatigue fracture   Since the coiled tubing have to constantly import or winding roller, it will be subjected to cyclic stress, and the well often has a corrosive medium erosion. Therefore, the working condition of the coiled tubing subjected to fatigue or corrosion fatigue is the most.

Surface damage failure

Surface damage mainly includes 3 forms:

• Corrosion   Including uniform corrosion (such as in a long time storage process leading to corrosion), pitting corrosion (such as the internal and external appearance pitting in the process of using or storing) and crevice corrosion (such as the corrosion between oil pipe welds and materials).
• Wear   The wear between the downhole tubing and casing or the wear between oil pipe and grip system for injection head and so on.
• Mechanical damage   Casing and tubing in transit surface bumps; The scratch of the wax scraper which falls into the well in the paraffin removal operation; In the injection process because of holding tight, left on the surface indentation.

Measures

Most of the tube failure accident occurred in the transition zone of the thickened transition, which accounted for 70%. The reason of failure is that the structure is not reasonable, resulting in stress concentration and corrosion fatigue. Central tube failure accident accounted for 30%. The cause of failure is the interaction of wall thickness thinning caused by abrasive wear and corrosion pit.


Proposed to strengthen the inspection of the pipe body before welding and deal with the serious internal corrosion to ensure the quality of the tube;
Ultrasonic inspection is carried out around the thickening transition zone of the oil pipe to check whether there is any defect in the transition zone. Length of transition zone and arc radius of oil pipe should be checked before welding, where thickened inner transition zone <100mm, R <300mm are not to be welded;
Strengthen the management of drilling fluid, the pH value of drilling fluid should be maintained at 10 or more than 10 under the condition permission.

Conclusion

With the increasing demand of the drilling industry, the oil pipe is easy to damage under the long-term high temperature and high pressure and unexpected accidents are common occurrence. So it is urgent and important to analyze the failure of tubing. Timely measures can improve the utilization of resources, avoid economic losses, and bring greater social and economic benefits.