In piping systems, elbows are pipe fittings that change the direction of the piping. According to the angle, there are three most commonly used ones: 45° and 90°180°, and other abnormal angle elbows such as 60° are also included according to engineering needs. Elbow materials include cast iron, stainless steel, alloy steel, malleable cast iron, carbon steel, non-ferrous metals and plastics. Purpose: To connect two pipes with the same or different nominal diameters, so that the pipes can make turns of 90°, 45°, 180° and various degrees.

The ways to connect with the pipe are: direct welding (the most commonly used way) flange connection, hot-melt connection, electric fusion connection, thread connection and socket connection, etc. According to the production process, it can be divided into: welding elbow, stamping elbow, push elbow, casting elbow, butt welding elbow, etc. Other names: 90-degree elbow, right-angle elbow, stamping elbow, pressed elbow, mechanism elbow, welding elbow, etc. Bending radius less than or equal to 1.5 times the pipe diameter belongs to the elbow, and greater than 1.5 times the pipe diameter belongs to the elbow.

Elbow production technical requirements:

1. Since most of the pipe fittings are used for welding, in order to improve the welding quality, the ends are beveled, leaving a certain angle and a certain side. This requirement is also relatively strict, such as how thick the side is, how much the angle is and the deviation The scope is specified. The surface quality and mechanical properties are basically the same as the pipe. For the convenience of welding, the steel grade of the pipe fittings and the pipes to be connected is the same.

2. All pipe fittings must undergo surface treatment, and the oxide scales on the inner and outer surfaces are sprayed off by shot blasting, and then coated with anti-corrosion paint. This is for export needs, and moreover, domestically, it is also for the convenience of transportation to prevent rust and oxidation, and work in this area must be done.

3. The requirements for packaging. For small pipe fittings, such as export, wooden boxes are required, about 1 cubic meter. It is stipulated that the number of elbows in this box should not exceed one ton. This standard allows packages, that is, large sets of small, But the total weight generally cannot exceed 1 ton. For large pieces y, they must be packaged individually, such as 24″, they must be packaged individually. In addition, there are packaging marks, which must indicate the size, steel number, batch number, manufacturer’s trademark, etc.

Elbow classification

1. Divided by material

Carbon Steel: ASTM/ASME A234 WPB, WPC

Alloys: ASTM/ASME A234 WP 1-WP 12-WP 11-WP 22-WP 5-WP 91-WP911, 15Mo3 15CrMoV, 35CrMoV

Stainless steel: ASTM/ASME A403 WP 304-304L-304H-304LN-304N

ASTM/ASME A403 WP 316-316L-316H-316LN-316N-316Ti

ASTM/ASME A403 WP 321-321H ASTM/ASME A403 WP 347-347H

Low temperature steel: ASTM/ASME A402 WPL3-WPL 6

High performance steel: ASTM/ASME A860 WPHY 42-46-52-60-65-70

Cast steel, alloy steel, stainless steel, copper, aluminum alloy, plastic, argon, PVC, PPR, RFPP (reinforced polypropylene), etc.

2. According to the production method, it can be divided into pushing, pressing, forging, casting, etc. 

3. According to the manufacturing standard, it can be divided into national standard, electric standard, ship standard, chemical standard, water standard, American standard, German standard, Japanese standard, Russian standard and so on.

4. According to its radius of curvature: it can be divided into long radius elbow and short radius elbow. A long radius elbow means that its radius of curvature is equal to 1.5 times the outer diameter of the pipe, that is, R=1.5D; a short radius elbow means that its radius of curvature is equal to the outer diameter of the pipe, that is, R=1.0D. (D is the diameter of the elbow, R is the radius of curvature). 

5. If divided according to the pressure level: there are about seventeen kinds, which are the same as the American pipe standards, including: Sch5s, Sch10s, Sch10, Sch20, Sch30, Sch40s, STD, Sch40, Sch60, Sch80s, XS; Sch80, SCH100, Sch120, Sch140, Sch160, XXS; STD and XS are the most commonly used. 

7. According to different shapes and uses, it can be divided into: grooved elbow, card sleeve elbow, double bearing elbow, flange elbow, different diameter elbow, seat elbow, inner and outer tooth elbow, stamping elbow , Push elbows, socket elbows, butt welding elbows, inner wire elbows, etc.

General Classification

Flexible elbow, ferrule elbow, edge elbow, quick fitting elbow, seat elbow, flange elbow, 180° elbow, double bearing elbow, single bearing elbow

Socket elbow, different diameter elbow, seamless elbow, butt welding elbow, 90° elbow, 45° elbow, combined tee internal thread elbow, stamping elbow, push elbow, high pressure elbow Wear-resistant elbows, mechanical elbows, flanged elbows, grooved elbows, three-dimensional elbows, external threaded elbows, threaded elbows, special elbows, waterproof elbows.

Elbow production standard: