Flanges Related Basic Knowledge Asked Questions

- May 14, 2018-

Q: What is loose flange? Where is the loose flange used and in what pipe fitting?

A: The loose flange is a movable flange piece, which is generally matched to the fittings for water supply and drainage. When the loose flange is out of factory, each flange at each end of the expansion joint has a flange, which is directly connected with the pipeline and equipment in the project by bolts.

Q: How is the flange connected to the pipe? What part of the welding is?

A: There are many kinds of flanges. Flat flanges, butt welding flanges and loose flanges are commonly used. Flat flanges are used for medium and low pressures, with insert welding and welding on both sides. The welding depth from flange sealing surface is 2-5mm. The butt welding flange can be directly butt welded, and the loose flange connections doesn’t need welded.

Q: What is flange form?

A: Flange is a link piece used to connect valves and pipes. When the valve is connected with the pipe, the connection is connected by bolts. Therefore, the two end faces of the valve have N uniform bolt holes, which are flange form.

Q: What kind of connection is the flange used?  

A: 1. Flange connection is an important connection mode of pipeline construction.

Flange connection means that the two pipes, fittings or equipment, first fixed on a flange, between the two flanges, plus flanged gaskets, bolts fastened together to complete the connection. Some pipe fittings and equipment have their own flange, and also belong to flange connection.

2. The flange is divided into threaded connection flanges and welded flanges. The low pressure and small diameter use the thread connection flange, the high pressure and the low pressure large diameter use the welding flange, the thickness of the flange of different pressure, the diameter and quantity of the connecting bolt are different.

3. According to the different levels of pressure, the flange gaskets also have different materials, such as low pressure asbestos pad, high pressure asbestos pad and metal pad.

4. Note that all the bolts must be tightened when the flange is connected, especially when the bolts are tightened.

Q: What are the problems to pay attention to when installing.

A: 1. The flange should have sufficient strength, not deformed when tightening. The flange sealing surface should be flat and clean. Carefully clean oil stains and rust spots during installation.

2. The gasket should have good oil and anti-aging properties, as well as better elasticity and mechanical strength. Installation should be based on the shape of the connection to choose different cross-section and size of the gasket, and placement is correct.

3. Flange fastening force should be uniform, and the compression of the pad should be controlled in about 1/3.