Carbon Steel End Cap Standard HG/T21635 Casing Cap 304/304L Material

Description

Mechanical Purpose: Pipe fittings that are welded at the end of the pipe or installed on the thread outside the end of the pipe to cover and plug the pipe. It is used to close the pipeline and has the same function as pipe plugging. The form of blind plate is similar, but the blind plate can be disassembled and blocked, while the welded pipe cap can not be disassembled.

The cap includes the design of convex cap, conical shell, variable diameter section, flat cover and contraction opening. The convex cap includes: hemispherical cap, elliptical cap, dish cap and spherical cap. Materials can also be divided into 20G, 20, Q235, Q345, Q345D, 16Mn, 12Cr1MoVG, 15CrMo, 304, 304L, 316L, 321, 2520, 310, 317 and other materials. Path: DN15-DN2020; Wall thickness: SCH5-SCH160-XXS

Standard: ASME DIN JIS BS GB/T JB SH HG,

Specifically as follows: GB/T 12459-2005, GB/T 13401-2005, ASME B16.9, SH3408, SH3409, HG/T 21635, DL/T695, SY/T 0510, DIN 2617

Uses: water, beverage, beer, food, petrochemical industry, nuclear power, machinery, medical equipment, chemical fertilizer, shipbuilding, waterproof treatment, pipeline, etc.

1. Large-mouth elliptical head splicing requirements; the carbon steel is first formed after the first slab, and the weld height of the weld that hinders the forming of the head should be polished and made flush with the base material before forming. The thickness after grinding shall not be less than the design thickness" and "the surface of the weld shall be allowed to be lower than the surface of the base metal, but shall not exceed 0.8 mm".

2. Elliptical heads are more common for medium pressure, and spin type heads are usually larger heads. First of all, what is the difference between the stamping type and the spinning type: the stamping is good, the head is broken, the size is guaranteed, but it is suitable for the small head. The spin forming is inferior, especially in the R section. The thickness is not uniform.

3. The metal in the heating zone of the elliptical head cannot be freely expanded due to the partition of the metal with a low ambient temperature. The head is not free to shrink due to the shrinkage of the surrounding metal after cooling. As a result, the partially heated metal has a tensile stress, while the other parts of the metal have a compressive stress balanced therewith. When these stresses exceed the yield limit of the metal, the seal will be deformed; when it exceeds the limit of the metal, the crack will occur.

4. The elliptical head depth is between the hemispherical and the dish-shaped head. For the requirements of the stamping equipment and the mold, the elliptical head is easier than the hemispherical head in the manufacturing difficulty, and is more difficult than the dish-shaped head. In recent years, the use of a spinning manufacturing process has facilitated the manufacture of a large-diameter elliptical head. Elliptical heads are widely used in medium and low pressure vessels because of their comprehensive properties.

The r part of the disc cap avoids splicing, which will reduce the thickness and increase the stress.

When splicing, only radial and circumferential weld directions are allowed. This requirement may be cancelled in the future for large pipe caps. The splicing distance shall be more than 3 δ and not less than 100 mm (the heat affected zone of welding is a high stress zone, and the chemical composition in the zone will be burnt. So avoid the high stress area, which is related to thickness. According to practical experience, the stress attenuation length is greater than 3 Delta and not less than 100 mm. But refrigeration equipment is difficult to meet this requirement, and has its particularity. After splicing, 100% X-ray or ultrasonic inspection should be carried out on the splicing weld of the formed head, and the qualified level should follow the equipment shell. The final weld inspection level and proportion are the same as the equipment shell. If the equipment shell is 20% inspected, III is qualified. The stitching weld and final weld of the stuffy head are also qualified for III, and the coefficient of weld joint is 0.85.

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