Head cap

A head cap is a pressure vessel in the boiler, is usually used in both ends of the pressure vessel. Then there is a kind of welding pipe product which is used for plugging at the end of the pipe. There are many forms.

The head cap is a part of the vessel which is connected in a welding type cylinder. (below) according to the different shape, can be divided into spherical, oval, dish shaped, spherical, conical shell and cover several, including spherical, oval, dish shaped, spherical head is also called convex head. The welding head is divided into butt welding head and socket welding head. It can be used in various containers, such as tanks, heat exchangers, towers, reactors, boilers and separation equipment, etc.. Materials are carbon steel (A3, 20#, Q235, Q345B, 16Mn, etc.), stainless steel (304, 321, 304L, 316, 316L, etc.), alloy steel (15Mo3 15CrMoV 35CrMoV 45CrMo), aluminum, titanium, copper, nickel and nickel alloy, etc..

The cap, the other name: head, head, head, pipe cap, bulkhead.

Use: welded pipe ends or installed on the outer thread of pipe ends to cover the pipe fittings. Used to seal the pipeline, the same effect as pipe plug.

The head cap includes the design of convex cap, conical shell, reducer, flat cover and tight mouth.

The convex cap includes a hemispherical, oval disc cap, cap and spherical cap. From the stress angle convex cap from the hemispherical cap is not good, but from look on the manufacturing difficulty, has good manufacturing.

Head cap parameters: stainless steel, alloy steel, carbon steel.

Path: DN15-DN1200

Wall thickness: SCH5-SCH160.

Standard: ASME DIN JIS BS GB/T JB SH HG, as follows: GB/T12459, GB/T13401, ASME B16.9, SH3408, SH3409, HG/T21635, DL/T695, SY/T0510, DIN2617

Uses: water, beverages, beer, food, petrochemicals, nuclear power, machinery, medical equipment, chemical fertilizer, shipbuilding, waterproofing, pipes, etc.

Packing: wooden box, carton service: provide technical advice, guidance, installation, etc.. R disc cap will avoid stitching, thinning, high stress.

The direction of weld seam is only radial and circumferential when stitching. After the large cap may cancel this request. The splicing distance should be greater than 3 and not less than 100mm (the welding heat affected zone is a high stress zone, and the chemical composition in the zone will be burnt. Therefore, to avoid the high stress zone, the area is related to the thickness. According to the practical experience, the stress attenuation length is greater than 3, and not less than 100mm. But refrigeration equipment is difficult to achieve this requirement, has its particularity.

The splicing head shall be tested by 100% - ray or ultrasonic inspection, and the qualification level will go along with the shell of the equipment. The level and proportion of formed weld detection are the same as that of equipment shell, so it is a waste.

Example: if the equipment shell is 20% detection, III qualified. The bulkhead welds and weld III welding joint is qualified, coefficient of 0.85;

If the equipment shell is tested, the II is qualified. The bulkhead welds and weld II welding joint is qualified, coefficient of 1, so although the bulkhead splicing detection, but the qualified level is not the same, go with the equipment shell.

But attention should be paid to the process of manufacturing:

The correct approach is: material (crossed) - plate into plate - molding - nondestructive testing, if not forming before detection is wrong, can not guarantee the qualified after molding. That is to say, nondestructive testing means the final nondestructive testing.