This technical specification is suitable for the bidding for the procurement of steel pipe projects.

Executive standards

The steel pipe shall meet the following standards:

Quality standard like Spiral Welded Submerged Arc Welded Steel Pipes for Urban Heating CJ/T3022-1993 or Technical Delivery Conditions of Oil and Gas Industry Transportation Steel Pipes GB/T9711.1-2017 should be implemented for spiral welded pipes.

Seamless Steel Pipe for Fluid Transportation GB/T8163-2008 should be carried out as quality standards for seamless steel pipes.

Technical requirements for steel pipes

Materials

The steel pipe should be made of spiral seam welded steel pipes with Q235B.  The seamless steel pipe should adopt 20# steel.

Technical specifications

The quality and size of spiral seam welded steel pipes should conform to IS09330-1 or GB9711.1～2017 standards.

Spiral seam welded steel pipes should ensure that the minimum yield strength is greater than 235N/mm2.

Weld joints of steel pipes must meet the technical requirements of DIN1626 or GB3323-87.

Specifications, weights and errors of steel pipes

The supply of steel pipes shall comply with the relevant regulations in the latest GB9711.1-2017 or GB8163-2008.

The normal supply length of the steel pipe should be 12m with a length deviation of 0/+25mm.  When the length of the steel pipe is less than 12m due to the valve, compensator or pipeline turning, it should be supplied according to the actual length on site.

The thickness deviation requirements of the raw material steel plate of the steel pipe: when DN is 800mm, the negative thickness deviation should be smaller than or equal to 0mm.  When DN is greater than 800 and smaller than or equal to 1100mm, the thickness negative deviation should be less than or equal to 0mm.  When DN is greater than 1100 and smaller than or equal to 1200mm, the thickness negative deviation should be less than or equal to 3%.

The end of the steel pipe should be grooved.  The groove angle should be 30° and the deviation 0°/5°.  The size of the blunt edge should be 1.6±0.8mm.

The end surface of the steel pipe shall be perpendicular to the axis of the steel pipe.  When the nominal outer diameter is less than 508mm, the limit deviation shall not be greater than 1.5mm.  When the nominal outer diameter is greater than or equal to 508, the limit deviation shall not be greater than 2.0mm.

The ovality of the steel pipe end within 100mm shall not exceed ±1%D.

Requirements for manufacturers

In order to ensure the quality of the project, the following requirements are put forward for the materials and manufacturers of steel pipes and fittings:

The steel quality standards of steel pipes are equal to or higher than those of famous steel pipe manufacturers in China.

The quality standard of the steel pipe is equal to or higher than the product standard produced by the bidder, and the selected manufacturer must be approved by the tenderer and indicate in the bidding document.

At the same time, photocopies of the delivery quality certificate of the steel pipe raw materials, the quality certificate of the steel pipe, the special equipment manufacturing license (pressure pipe) that the manufacturer should have, and the inspection report issued by the local quality inspection department must be attached to the bidding documents.

Seamless steel pipe is a kind of long steel with hollow section and no joint around.  The seamless steel pipe has hollow section and can be used as the pipeline for conveying fluid, such as oil, natural gas, gas, water and some solid materials.  Compared with solid steel such as round steel, seamless steel pipe is lighter in weight when its bending and torsion strength is the same.  It is a kind of economic section steel, which is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automobile transmission shaft, bicycle frame and steel scaffold used in construction.  Using seamless steel pipe to make annular parts can improve the material utilization rate, simplify the manufacturing process, save materials and working hours, such as rolling bearing rings, Jack sleeves and so on.  Steel pipe is also an indispensable material for all kinds of conventional weapons.  Gun barrel and barrel should be made of steel pipe.

According to different production methods, it can be divided into hot-rolled pipe, cold-rolled pipe, cold drawn pipe, extruded pipe, etc.

1.Hot rolled seamless steel pipe is usually produced on the automatic pipe mill.  After checking and removing the surface defects of the solid tube blank, it is cut into the required length, centring on the end face of the piercing end of the tube blank, and then sent to the heating furnace for heating and piercing on the piercing machine.  In the process of piercing, a cavity is gradually formed inside the tube blank under the action of the roller and the plug, which is called the blank tube.  Then it is sent to the automatic pipe rolling mill to continue rolling.  Finally, the wall thickness is adjusted by the whole machine, and the diameter is calibrated by the sizing machine to meet the specification requirements.  It is an advanced method to produce hot rolled seamless steel tube by continuous pipe mill.

2.  In order to obtain smaller size and better quality seamless tubes, cold rolling, cold drawing or a combination of both must be used.  Cold rolling is usually carried out on a two high mill.  The steel tube is rolled in an annular pass composed of a variable cross-section circular groove and a stationary conical plug.  Cold drawing is usually carried out on 0.5-100t single chain or double chain cold drawing machines.

3.  In extrusion process, the heated tube blank is placed in a closed extrusion cylinder, and the piercing rod and the extrusion rod move together to extrude the extruded part from the smaller die hole.  This method can produce small diameter steel pipe.

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Are you tired of loud and abrupt door closures? The soft closing invisible roller and track kit is the perfect solution for those looking to upgrade their door system with a smooth and quiet closing mechanism. In this step-by-step guide, we will walk you through the process of installing and using this innovative kit. Let’s get started!

Step 1: Gather the Necessary Tools and Materials

Before you begin, make sure you have all the required tools and materials handy. You will need:

• Soft closing invisible roller and track kit (including rollers, tracks, and mounting accessories)

• Measuring tape

• Pencil

• Screwdriver

• Level

Step 2: Measure and Mark

Start by measuring the height and width of your door opening. Use a measuring tape to ensure accurate measurements. Based on the dimensions, mark the desired position of the roller and track on the door frame and the top of the door.

Step 3: Install the Rollers

Next, install the rollers on the top of the door. Align the rollers with the marked positions, making sure they are level. Using a screwdriver, secure the rollers tightly to the door.

Step 4: Attach the Track

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Now that everything is properly installed, you can experience the benefits of the soft closing feature. Each time you close the door, the rollers will engage, providing a controlled and noise-free closure. Bid farewell to slamming doors!

Conclusion

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Note: The word count of this article is approximately 350 words.

During the stamping production, the punch drives the die to move back and forth, which determines that the processing accuracy of the stamping products is mainly affected by the following three aspects, namely, the size and accuracy of the die, the accuracy of the die fitting, and the accuracy of the punch.

1. Influence of die size and precision on the precision of stamping products

Stamping products will have their own elastic recovery, elastic deformation of the mold and temperature rise caused by deformation during forming. The deviation between the product and the mold size will affect the accuracy of stamping products.

2. Influence of die fitting accuracy on stamping product accuracy

During the work of the punch, the slider and the master die are often installed into the die-set module with guide posts to maintain the centering accuracy. If the solid guide posts are not used, it is difficult to maintain the accuracy, which will lead to improper alignment of the dies and cause the products to be inward, misaligned and bent.

3. The influence of punch's own precision on the precision of stamping products

The body, worktable, sliding block and other structural parts of the punch press and the forging die will all produce changes in elastic deformation. The elastic deformation error between the punch and the die is the accuracy of the bottom dead center position of the punch slider, which can also be called the dynamic accuracy of the punch when the punch is loaded, and determines the forging processing accuracy of the bottom thickness and flange thickness of the stamped product.

The accuracy of a punch is usually expressed by its static accuracy and rigidity. The accuracy grade under static state can be divided into special grade, grade 1, grade 2 and grade 3 according to the static accuracy index of JIS punch in Japan. For the punch, the static grade is a major factor, but the rigidity of the punch is also an important factor that cannot be ignored, which is the strength of the punch.