Summary of common knowledge of flanges

Flange, or flange, also translated as rim or flange, also translated as "Buddha Leng" in Cantonese, means a symmetrical disc-like structure used to connect pipes, containers or fixed shaft mechanical parts, usually with bolts and threaded structures for fixing.

 

Introduction

The flange is the main part of the flange connection. FA flange connection is a pair of flanges, sealing gaskets and bolts, nuts, washers and other parts composed of detachable parts.

 

The main parameters of the standard flange are nominal diameter, nominal pressure and sealing surface type.

 

Classification

1, according to the chemical (HG) industry standards: integral flange (IF), threaded flange (Th), plate flat welding flange (PL), necked butt welding flange (WN), necked flat welding flange (SO), socket welding flange (SW), butt welding ring loose flange (PJ/SE), flat welding ring loose flange (PJ/RJ), lined flange cover (BL(S)), flange cover (BL).

2, according to the petrochemical (SH) industry standards: threaded flange (PT), butt welding flange (WN), flat welding flange (SO), socket welding flange (SW), loose flange (LJ), flange cover (not table note).

3, according to the machinery (JB) industry standards: the whole flange, butt welding flange, plate flat welding flange, butt welding ring plate loose flange, flat welding ring plate loose flange, flanged ring plate loose flange, flange cover.

4, according to the national (GB) standard: the whole flange, threaded flange, butt welding flange, necked flat welding flange, necked socket welding flange, butt welding ring-necked loose set flange, plate type flat welding flange, butt welding ring plate type loose set flange, flat welding ring plate type loose set flange, flanged ring plate type loose set flange, flange cover.

 

Material

WCB (carbon steel), LCB (low-temperature carbon steel), LC3 (3.5% nickel steel), WC5 (1.25% chromium 0.5% molybdenum steel), WC9 (2.25% chromium), C5 (5% chromium 0.5% molybdenum), C12 (9% chromium 1% molybdenum), CA6NM (4 (12% chromium steel), CA15 (4) (12% chromium), CF8M (316 stainless steel), CF8C (347 stainless steel), CF8 (304 stainless steel), CF3 (304L stainless steel), CF3M (316L stainless steel), CN7M (alloy steel), M35-1 (Monel), N7M (Hastelloy B), CW6M (Hastelloy C), CY40 (Inconel), etc.

 

Connection method

Flange connection is the two pipes, fittings or equipment, each fixed in a flange, between the two flanges, plus the flange gasket, bolted together, completed the connection. Some pipe fittings and equipment already comes with a flange, which is also a flange connection. Flange connection is an important connection method for pipeline construction. Flange connections are easy to use and can withstand large pressures. In industrial piping, within the home, the pipe diameter is small and it is low pressure and the flange connection is not visible. If you are in a boiler room or production site, there are flange-connected pipes and equipment everywhere.

 

According to the connection method flange connection types can be divided into plate flat welding flange, necked flat welding flange, necked butt welding flange, socket welding flange, threaded flange, flange cover, necked butt welding ring loose flange, flat welding ring loose flange, ring groove surface flange and flange cover, large-diameter flat flange, large diameter high neck flange, eight blind, butt welding ring loose flange, etc.

 

Welding quality

As iron plate welding flange, many customers question if the quality of iron plate welding flange is better than wrought welding flange. In fact, the quality of iron plate welding flange and forged welding flange quality is the same, but the iron plate welding flange in the end can not be guaranteed, that is, the material of the iron plate welding flange is not guaranteed, because the general process, the density of iron plate welding flange is not a problem, but in the process of production, the iron plate welding flange blank is rarely tested, so that the production After coming out, the material of the iron plate welding flange can not be guaranteed without testing.

 

Production standards

National standard: GB/T9112-2010 (GB9113-1-2010 ~ GB9123-4-2010)

Ministry of Chemical Industry standards: HG5010-52 ~ HG5028-58, HGJ44-91 ~ HGJ65-91, HG20592-2009 series, HG20615-2009 series

Ministry of Machinery standards: JB81-59 ~ JB86-59, JB/T79-94 ~ JB/T86-94, JB/T74-1994

Pressure vessel standards: JB1157-82～JB1160-82, NB/T47020-2012～NB/T47027-2012, B16.47A/B B16.39 B16.

 

Standard system

The international pipe flange standard mainly has two systems, namely, the European pipe flange system represented by Germany DIN (including the former Soviet Union) and the American pipe flange system represented by the American ANSI pipe flange. In addition, there are Japanese JIS pipe flanges, but petrochemical plants are generally used only for public works and have less impact on the international level. Now the pipe flanges of various countries are introduced in the following.

1, Germany and the former Soviet Union as the representative of the European system pipe flange

2, the American system pipe flange standards, represented by ANSI B16.5 and ANSI B 16.47

3, the British and French pipe flange standards, two sets of pipe flange standards in each country.

In summary, the international common pipe flange standards can be summarized as two different, and not interchangeable pipe flange systems: a European pipe flange system represented by Germany; the other is the American pipe flange system represented by the United States.

IOS7005-1 is a standard promulgated by the International Organization for Standardization in 1992, which is actually a pipe flange standard that combines two series of pipe flanges from the United States and Germany

 

Common failures

In the continuous production of modern industry flange by media corrosion, scouring, temperature, pressure, vibration and other factors, there will be inevitable leakage problems. Due to the error of the sealing surface processing size, sealing components of aging and improper installation and fastening and other reasons are very easy to cause the flange leakage. If the flange leakage problem can not be time management, the washout of the medium will make leakage rapidly expand, resulting in material loss, damage to the production environment, resulting in enterprise downtime, resulting in huge economic losses. If it is toxic and harmful, flammable and explosive media leakage, and may cause poisoning, fire and explosion and other major accidents.

The traditional solution for flange leakage is to replace the sealing components and apply sealant or replace the flange and piping, but the method has great limitations, and some leakage is restricted by the requirements of the safety of the working environment, and can not be solved on-site. Now it is possible to use polymer composite materials for on-site plugging, of which the application is more mature with the system of Fushi Blue. It is a very ideal method, especially on flammable and explosive occasions, but also to show its unique superiority. The construction process of polymer composite material technology is simple, safe and low cost, which can solve most of the flange leakage problems for enterprises, eliminate safety hazards and save more maintenance costs for enterprises.

 

Scope of application

Because the flange has good comprehensive performance, it is widely used in the chemical industry, construction, water supply, drainage, petroleum, light and heavy industry, refrigeration, sanitation, plumbing, fire-fighting, electric power, and aerospace, shipbuilding and another basic engineering.