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Visual Inspection
Visual Inspection is one of the most effective inspection method used to check overall product quality. During the visual inspection, you will check for the overall product finish.
You will check for surface imperfections such as mechanical marks, lamination, tears or any other visual imperfections and also check weld defects such as porosity, undercuts, uneven weld bead, and excess or underfill of weld material. Acceptance of these imperfections is as per applicable ASTM standard.
Dimension inspection of the pipe is carried out based on the Dimension Standard, the final dimension of the pipe must confirm the following standard or it should be as specified in the purchaser’s specification.
- For Welded and Seamless Wrought Steel Pipe dimensional requirements are cover in ASME B36.10
- For Stainless Steel Pipe dimensional requirements are cover in ASME B36.19
During a dimensional inspection, following to be confirmed with standard
- Diameter
- Length
- Thickness
- Straightness
- Ovality &Weight
Permissible Variations depends on manufacturing standard.
Pipe Coating
Corrosion prevention of pipes refers to measures to slow down or prevent corrosion and deterioration of pipes under the chemical or electrochemical action of the internal and external media or by the metabolic activities of microorganisms.
Why do seamless steel pipes need to be anticorrosive?
Seamless steel pipe is a relatively high-end steel pipe. After all, the raw material is iron, which will also rust, which will affect the service life in the pipeline. Therefore, the anticorrosion of seamless steel pipe is also a process that must be done before pipeline construction. For seamless steel pipe It is mainly used for 3pe anticorrosion or epoxy coal tar anticorrosion.
Seamless steel pipe anti-corrosion process
The anti-corrosion of the steel pipe is according to the requirements of the drawings, and the epoxy coal tar paint is used to wrap the glass cloth, and the top paint is coated for anti-corrosion.
Outer wall construction process: pipeline derusting → primer coating → first pass top coat → second pass top coat → wrap glass cloth → top coat → top coat;
Inner wall construction process: pipeline derusting→primer coating→first pass top coat→second pass top coat→third pass top coat
Anticorrosive technology of spiral steel pipe
In the process of anti-corrosion spiral steel pipe, there are two-cloth and three-oil anti-corrosion, that is, three times of epoxy coal tar anti-corrosion paint and two layers of glass cloth. People are also used to call three-oil and two-cloth anti-corrosion spiral steel pipe. The following is the anti-corrosion process.
Primary treatment-primer-first application-applique-second application-second application-third application-fourth application-inspection and supplement.
Anti-corrosion construction site
Anticorrosive spiral steel pipe note:
- The timing of applying the cloth can be done after the paint is dried, or it can be applied immediately after the paint is applied. It should be treated according to specific coatings.
- The brushing interval should be adjusted according to the drying time of the seasoning. The drying time of various coatings is different.
- The direction of each brushing should be perpendicular to the direction of the last brushing, that is, cross brushing.
Steel pipe anticorrosive material
Anticorrosive pipeline materials mainly include 2/3P anticorrosion (polyethylene), 2/3PE anticorrosion (polypropylene), single layer epoxy powder anticorrosion, epoxy coal tar anticorrosion, etc.
3PE anticorrosive steel pipe
3PE anticorrosive steel pipe base materials include seamless steel pipes, spiral steel pipes and straight seam steel pipes. The three-layer polyethylene (3PE) anticorrosive coating has been widely used in the petroleum pipeline industry due to its good corrosion resistance, water vapor permeability and mechanical properties. The anti-corrosion layer of 3PE anti-corrosion steel pipe is very important to the life of buried pipelines. Some pipelines of the same material will not corrode after being buried in the ground for decades, and some will leak in a few years. It is because they use different outer anti-corrosion layers.
Anti-corrosion form of outer wall of steel pipe
3PE anticorrosion generally consists of 3 layers
- One layer of epoxy powder (FBE>100um)
- Two-layer adhesive (AD) 170～250um
- Three-layer polyethylene (PE) 1.8～3.7mm
In actual operation, the three materials are mixed and integrated, and processed to form an excellent anti-corrosion layer firmly combined with the steel pipe. The processing method is generally divided into two types: winding type and round mold covering type.
3PE anti-corrosion steel pipe coating is (three-layer polyethylene anti-corrosion coating), which is a new kind of anti-corrosion produced by cleverly combining 2PE anti-corrosion coating in Europe and epoxy powder anti-corrosion steel pipe coating (FBE) widely used in North America Steel pipe coating. It has been recognized and used all over the world for more than ten years.
The coating of 3PE anticorrosive steel pipe is the epoxy powder anticorrosive coating between the bottom layer and the surface of the steel pipe, and the intermediate layer is a copolymer adhesive with branch structure functional groups. The surface layer is a high-density polyethylene anticorrosive coating.
3PE anticorrosive coating combines the high impermeability and mechanical properties of epoxy resin and polyethylene materials. So far, it has been recognized globally as a pipeline anti-corrosion coating with good use effect and high performance, which has been applied in many projects.
Advantages of 3PE anticorrosive steel pipe
- PE anticorrosive pipeline has extremely high sealing performance, long-term operation can greatly save energy, reduce costs and protect the environment.
- Strong corrosion resistance, simple and quick construction, and the service life can reach 30-50 years.
- It also has good corrosion resistance and impact resistance under low temperature conditions, and the PE water absorption rate is low (less than 0.01%).
- At the same time, it has high epoxy strength, low water absorption of PE and good softness of hot melt adhesive. It has high anti-corrosion reliability. The disadvantage is that compared with the cost of other splicing materials, the cost is high.
Epoxy powder dipping anticorrosion process
Epoxy powder has always been applied by electrostatic spraying. Since the epoxy powder dipping process is troubled by adhesion problems, the dipping of epoxy powder has never been promoted. In recent years, with the successful development of the special phosphating solution for epoxy powder dipping, the epoxy powder dipping process has overcome the adhesion problem for the first time, and the emerging process of epoxy powder dipping has begun to be promoted.
Anti-corrosion construction
Construction principles
The quality of coating construction has a great influence on the performance of the coating. In the actual coating process, there are many examples of failure to achieve the expected anti-corrosion effect due to improper construction methods. In particular, many anti-corrosion coatings with excellent performance are extremely sensitive to the construction method, and only when they are constructed strictly in accordance with their respective construction conditions can they form a normal coating and achieve the expected anti-corrosion protection effect.
- The substrate must undergo strict surface treatment
The steel base material must undergo derusting and degreasing treatment, and the phosphating treatment can be determined according to specific conditions. - To ensure the necessary coating thickness
The thickness of the anti-corrosion coating must exceed its critical thickness in order to play a protective role, generally 150μm ~ 200μm. - Control environmental factors such as temperature and humidity at the painting site
The indoor coating temperature should be controlled at 20℃～25℃; the relative humidity varies depending on the variety, generally around 65% is appropriate. There should be no wind, sand or drizzle during outdoor construction, the temperature should not be lower than 5℃, and the relative humidity should not be higher than 85%. Frost, dew, rain, and falling sand and dust on the incompletely cured coating should be avoided. - Control the coating interval time
If the primer is left for too long before the topcoat is applied, it will be difficult to adhere and affect the overall protective effect.In addition, the training of construction personnel and construction quality management must be strengthened. The construction personnel are required to understand the nature, usage, construction points and technical requirements of the coating.
Managers must strengthen quality control to ensure that each process meets the technical requirements in order to finally obtain an excellent anti-corrosion coating. It is also necessary to strengthen labor safety protection, pay attention to solvent volatilization, and strengthen ventilation to avoid poisoning.
Cut to length
No matter the material, measure the diameter of the pipe or tube to be cut to ensure that you use the right-size tube cutter for the job.
Before Cutting Pipe and Tubing
No matter the material, measure the diameter of the pipe or tube to be cut to ensure that you use the right-size tube cutter for the job.
When determining how to make a straight cut, use a tape measure and a pencil or other writing instrument to mark on the surface where you want to cut. If possible, mark around the circumference of a pipe, especially when cutting with a handsaw.
Ensure that a cut is as straight as possible by securing the pipe with a vise, clamp, miter box or even duct tape to keep the length from shifting out of place while cutting.
Cutting Ways
Many factors are involved in choosing a particular method or technology for cutting tube or pipe. The basic factors that affect the cut are the tube or pipe material, wall thickness, squareness of ends, end-conditioning requirements, and secondary process requirements.Other factors that play a role include production volume, cutting efficiency, overhead costs, and special requirements of the tube or pipe material.
Abrasive Cutting
Abrasive sawing is a basic, manual method of cutting-to-length product to the customer’s specification in any alloy.
Band Saw Cutting
Band saw cutting is a fully automatic process and the most common method for cutting rod, bar, pipe, and tubing. This process is excellent for large-volume cutting. Some band saws can handle large product bundles.
Cold Sawing
High-precision cold sawing is suitable for cutting smaller-diameter or thin-walled material that requires tight tolerances. A circular cold saw uses a wheel blade and cutting fluid, which usually is applied with a mist lubricator.
Laser Cutting
Despite the high capital cost, a laser cutting system provides a range of capabilities and associated advantages. Easily controlled with automation equipment (CNC), a laser allows an operator to cut, deburr, inspect, and even pack material while the laser runs continuously.
Lathe Cutting
Lathe cutting is ideal for thin-walled material, producing square cut ends with minimum burr. Multiple cross slides permit deburring orchamfering the OD of both ends during the lathe cutting process.
Shearing
A tube shear is a completely automatic, high-speed machine that uses two shearing plates and two ID punches under extreme pressure to cut tubing. The shearing action is the same for all sizes and wall thicknesses with maximum limits
Transport
Transporting steel pipe by barge is the primary shipping method when importing or exporting pipe out of North America. Barges can hold, on average, up to 1500 tons of material.
Barge
Transporting steel pipe by barge is the primary shipping method when importing or exporting pipe out of North America. Barges can hold, on average, up to 1500 tons of material. This enables shipment of a large quantity of product at an economical price point. Barge shipments are also used within the USA and Canada to move large product quantities to locations on or near water.
Truck
Trucks are the most common shipping method of steel pipe across Canada and the US. In Canada, trucks can haul a payload of approximately 46,000 to 80,000 lbs, depending on the source and destination of the product and the type of trailer being utilized for shipment. Tandem trailers can haul 46,000 lbs payload, triaxle trailers can haul 60,000 lbs. Quad axle trailers can haul a total payload of around 80,000 lbs.
Rail
Rail transportation is a good option when moving large quantities of pipe across North America, especially in longer lengths, which can be expensive when shipping by truck as they often require pilot cars and permits. There are two types of cars that enable hauling of steel pipe. The first, is a gondola, which is a car with sides that pipe can be loaded into loosely. The second type is a flat car; the base is flat and it has no sides, allowing pipe to be stacked and loaded in layers with contoured dunnage between.
Packing & Marking
Packing
Packaging is the technology of enclosing or protecting products for distribution, storage, sale, and use. There are probably hundreds of different methods for packing a pipe, Our packaging for pipe, tube, fittings and flange are critical to minimising product damage.
Marking
Finished Products Like Pipes/Tubes/Fittings/Bars are marked with Electric Etching/Electronic Inkjet Marking machine.
Each Product is marked with “Manufacturers Logo, Name, Size, Specification, Grade, Heat No. or as per Customer Requirements.
For example:
Marking Requirements of ASTM A53 Steel Pipe
- Manufacturer’s name or mark
- Specification number (year-date not required),
- Size (NPS and weight class, schedule number, or specified wall thickness; or specified outside diameter and specified wall thickness),
- Grade (A or B),
- Type of pipe (F, E, or S),
- Test pressure, seamless pipe only.
- Nondestructive electric test, seamless pipe only.
Pipe beveling
Beveling of pipe or tubing is most commonly used to prepare the ends for welding. It can also be used for deburring the cut ends for safety and aesthetic reasons.
What is pipeline beveled end and why use it?
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. Beveling of pipe or tubing is most commonly used to prepare the ends for welding. It can also be used for deburring the cut ends for safety and aesthetic reasons.
Subtract the pipe’s wall thickness from the pipe’s outside diameter. For example, if you had a pipe with a diameter of six inches and a wall thickness of two inches, you would subtract two from six to get four.
Why bevel a pipe?
Beveling of pipe or tubing is most commonly used to prepare the ends for welding. It can also be used for deburring the cut ends for safety and aesthetic reasons.
Common types of beveled ends
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.
Pipe threading
Common pipe thread types:
NPT or NPS (national pipe tapered or straight): Most common in North America
MIP or FIP (male or female iron pipe): Same thread dimensions as NPT
BSP(T) or BSP(S) (British standard pipe tapered or straight): Most common in Europe
Compression: A unique threaded fitting that does not mate with other thread types
UNS (National Unified Special): Some compatible with compression fittings
What are the parts of a pipe thread?
The thread dimension refers to the major diameter or outside measurement.
The pitch is the distance from the peak of one crest to the opposite of another.
The thread angle is the difference between the threads or the valley between the peaks.
Mechanical inspections
Product Analysis – Chemical & Mechanical Testing of Pipe
Metallurgical Tests
Metallurgical Tests confirm that the chemical requirements of pipe are as per the material standard.
Metallurgical Tests are normally known as Micro and Macro pipe inspection & testing.
Micro Analysis or Chemical Analysis of
Raw material
Product
Weld ensures that all the alloying elements are within the range as specified in the material standard
Macro Analysis for Weld will check the proper fusion of weld material with pipe material.
There are some Special pipe inspection tests also carried out on the material when it is going to be used in aggressive environments. These tests will ensure that pipe material is able to withstand in such aggressive environments also. Some of the tests are
Grain size (AS & SS)
IGC- Intergranular Corrosion Test(SS)
Ferrite (SS)
HIC- Hydrogen-induced Cracking
SSC- Sulfide Stress Corrosion Cracking
These tests are performed when it is asked by the purchaser in his specification.
Destructive test
The mechanical / Destructive test of pipe inspection confirms the mechanical requirements of pipe are as per the material standard.
In Destructive Testing- a sample from the pipe is cut to performed tests
The tensile test is done to check the yield and ultimate tensile of the pipe. If required by the purchaser or by standard high or low-temperature tensile tests are also performed.
Bend test / Guided bend test is used to check the integrity of weld joint
Flattening test examines the ability of plastic deformation in a pipe
Impact test / Charpy V-Notch Test, check the ability of a material to withstand under low-temperature conditions
Creep test is done to check the long term effect of temperature under constant load.
Packaging inspection
To prevent the damage during transportation, pipe ends are covered with a cap. Spider supports at the end of the pipe are also installed in Large diameter pipe to protect the circularity of pipe.
Pipe Marking Inspection
Once the pipe is cleared all test and inspection, it is marked as per the standard requirements
The following shall be marked on the pipe
Manufacturer logo
ASTM material code
Material Grade
Size
Thickness- schedule no.
Length
Heat No
Special marking WR for weld repair or NH for the non-hydro tested pipe.
These Marking can be done by paint or by Hard punching
For stainless steel, pipe stenciling is also used
Please note that
For carbon steel no hard-punching below 6 mm thickness
For stainless steel no hard-punching below 12 mm thickness