Welding flange

Welding flanges are parts that are connected to the pipe and connected to the pipe ends. The welding flange has holes in it, and the bolts make the two flanges tighten. Seal with gasket. Welding flange is a kind of disc parts, which is more common in pipeline engineering.

Welding flange (flange) connection is to attach two pipes, fittings, or equipment, each to a welding. The two welding joints, with flange pads, are bolted together to complete the connection. Welding is an important connection mode for high pressure pipeline construction. Welding flange connection is convenient and can withstand great pressure. Welding flange is widely used in petroleum, chemical, natural gas, power station, metallurgical pipeline and other fields.

Welding flange standard system

There are two main systems for international flanges, namely the European tube flanges system represented by German DIN (including the former Soviet union) and the American tube flange system represented by the American ANSI tube flange. In addition, there are Japanese JIS tube flanges, but in petrochemical installations, they are generally used only for public works and have little international impact. Now the country's flanges are introduced:

(1) European system tube flanges represented by Germany and the former Soviet union

(2) standard of American system pipe flange, represented by ANSI B16.5 and ANSI B 16.47

(3) British and French pipe flange standards, each of which has two pipe flange standards.

To sum up, the international standard of tube flanges can be summarized into two different and uninterchangeable pipe flange systems: a European tube flange system represented by Germany; The other is a system of American tube flanges represented by the United States.

Ios7005-1 is a standard adopted by the international organization for standardization in 1992, which effectively combines the two sets of pipe flanges in the United States and Germany.

The relevant standard

Hg20593-2009 hg20615-2009 national standard: GB/t9119-2000 GB/t2555-81 machinery standard: JB/t81-94 JB/t74-94 JB/t74-94 JB/t74-94 JB/t75-94 Marine standard: use of pressure b, pn0.0.mpa, pn0.6mpa, pn1.6mpa, pn2.5mpa, pn4.mpa

The relevant classification

1, according to the chemical industry norm: integral flange (IF), threaded flange (Th), plate (PL) flat welding flange, butt welding flange with diameter (WN), with flat welding neck flange, socket welding flange (SO) (SW), the butt welding ring loose flange (PJ/SE), flat welding ring loose flange (PJ/RJ), lining flange cover (BL (S)), flange cover (BL).

2. Standard points in petrochemical industry: threaded flange (PT), welding flange (WN), plain welding flange (SO), socket welding flange (SW), loose cover flange (LJ), flange cover (not note).

3, according to the mechanical industry norm: integral flange, butt welding flange, plate flat welding flange, butt welding plate loose flange rings, flat welding ring plate loose flange, flange ring plate loose flange, flange cover. 4, according to the national norm: integral flange, threaded flange, butt welding flange, with flat welding neck flange, socket welding neck flange, butt welding band neck loose flange, plate, flat welding flange, butt welding plate loose flange rings, flat welding ring plate loose flange, flange ring plate loose flange, flange cover.

Basic material

Nickel steel), WC5 (1.25% 0.5% chrome molybdenum steel), WC9 chromium (2.25%), C5 (% 5% chromium molybdenum), C12 (9% 1% chromium molybdenum), CA6NM (4 (12% chromium steel), CA15 (4) (12% chromium), CF8M stainless steel (316), CF8C stainless steel (347), CF8 stainless steel (304), CF3 (304 l stainless steel), CF3M (316 l stainless steel), CN7M (alloy), (monel), N7M M35-1 (B) hastert nickel alloy, CW6M nickel alloy C (haas tower), CY40 nickel alloy, because of)

Flange butt welding standard:

National standard: GB/t9119-2000gb/t2555-81

Machinery standards: JB/t81-94jb/t74-94jb/t75-94

Marine standard: CB m1001-81

Welding process

Equipment and tools required

One set of manual welding equipment, handle type Angle grinder, electric hammer, plane ruler.

Weld preparation

1. Check and debug the equipment to ensure the normal operation of the equipment;

2. Prepare phi 4.0 J506 welding rod is in 300 ℃ to 350 ℃ drying for one hour.

Welding process

1. Assemble the vertebral body and large flange according to the drawing requirements, and then divide the large flange into equal parts.

2. Welding because of the thick flange, the groove is larger, so it adopts segmented symmetry and multi-layer welding.

Weld quality

The weld strength shall be at least the strength of the parent material. The weld surface is smooth and smooth, without burning, air hole, welding leakage, slag, bit edge, unsoldered. The remaining height is less than 2mm.

considerations

1. Use J506 welding rod for manual surfacing and small current welding. Strictly follow welding process.

2. After each welding position, the deflection of the flange plane should be used with a horizontal ruler.

3. Weld with air hammer to achieve the effect of eliminating stress while welding.

Scope of application

Due to the welding flanges with good comprehensive performance, so it is widely used in chemical industry, construction, water supply, water drainage, oil, light and heavy industry, freezing, sanitary, plumbing, fire protection, electric power, aerospace, shipbuilding and other basic engineering.