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Introduce of carbon steel cap
- Aug 21, 2018 -

Introduce of carbon steel cap

Cap, also known as head, plug, cap, pipe cap, stuffy head, welded in the pipe end or installed in the pipe end on the outside thread to cover pipe plugging fittings. It is used to seal the pipeline, and its function is the same as that of pipe plugging.
The cap and the blind plate are similar in form, but the blind plate can be removed and plugged, while the welded cap can not be removed. The tube cap includes a convex tube cap, a conical shell, a variable diameter section, a flat cover and a tightening port design.
The convex tube cap comprises a hemispherical tube cap, an elliptical pipe cap, a disc shaped pipe cap and a spherical cap tube cap. From the point of view of force, the hemispherical pipe cap in the convex pipe cap is gradually not good, but from the point of view of manufacturing difficulty, it is gradually easy to manufacture.
Stainless steel: 304 304L 316 316L 3212520310, 317, and other materials.
Path: DN15-DN1200
Wall thickness: SCH5-SCH160
Standards: ASME DIN JIS BS GB/T JB SH HG, as follows: GB/T12459-2005, GB/T13401-2005, ASME B16.9, SH3408,
SH3409, HG/T21635, DL/T695, SY/T0510, DIN2617
Usage: Water, beverage, beer, food, petrochemical, nuclear power, machinery, medical equipment, fertilizer, shipbuilding, waterproof treatment, pipeline, etc.
Packing: wooden cases, cartons

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The R of the dish cap can avoid splicing, which will reduce the thickness and stress.
Welding direction is only allowed to be radial and circumferential when splicing. Large caps may cancel this requirement later. The splicing distance should be greater than 3 Delta and not less than 100 mm (welding heat affected zone is a high stress zone, and the chemical composition in this zone will be burned out. Therefore, to avoid high stress area, the area is related to thickness. According to practical experience, the stress attenuation length is greater than 3 100mm and is not less than 0. But refrigeration equipment is difficult to achieve this requirement, and has its particularity.
The head formed after splicing shall be inspected by 100% X-ray or ultrasonic wave, and the qualified level shall follow the shell of the equipment. The final weld inspection level and proportion are the same as that of the equipment shell, which is high waste. Example: if the equipment shell is 20% tested, III is qualified. The III is qualified and the welding joint coefficient is 0.85.
If the equipment shell is 100% tested, II is qualified. The II is qualified and the welding joint coefficient is 1.
Therefore, although 100% tests are made, the qualification level is different.
But pay attention to the process of manufacturing.
The correct way is: cutting (scribing) - the small board is made of big board - forming - nondestructive testing.
If the test is not done before it is formed, it will not guarantee the quality of the product after molding. In other words, NDT is the ultimate NDT.