Stainless Seamless Steel Pipe, 304 Stainless Pipe, 316 Stainless Pipe

Stainless Seamless Steel Pipe

Stainless steel seamless pipes are made from solid round billets with hollow sections and no welds. They are typically used in high-pressure applications such as hydrocarbon industries and refineries, oil and gas exploration and transportation. They are available in sizes and wall thicknesses ranging from 1/8 inch to 26 inch OD.

Sizes of Stainless Seamless Steel Pipe

Product specifications

Serial Number	Product	Outer Diameter (OD) (mm)	Wall Thickness (WT) (mm)
1	Cold Drawn Tube	φ6 - φ1016	φ1 - φ50.01
2	Cold Drawn Tube	φ16 - φ325	φ1 - φ30

Stainless Steel Seamless Pipe (Cold Drawn, Cold Rolled, Bright)

Product	Outer Diameter (OD) (mm)	Wall Thickness (WT) (mm)	Length (m)
Stainless Steel Seamless Pipe	6--20	0.8 - 3.5	Max: 240
Stainless Steel Seamless Pipe	20 - 32	1.5 - 8	Max: 24
Stainless Steel Seamless Pipe	32 - 159	1.5 - 35	Max: 12
Stainless Steel Seamless Pipe	168 - 325	3 - 40	Max: 12
Stainless Steel Seamless Pipe	325 - 830	5.5 - 45	Max: 8.5

General specifications and appearance quality

A. According to GB14975-2002 "Seamless Stainless Steel Pipe", the usual length of steel pipe (not fixed length) is 1.5 to 10m for hot-rolled steel pipe and equal to or greater than 1m for hot-extruded steel pipe. For cold-drawn (rolled) steel pipe with a wall thickness of 0.5 to 1.0mm, it is 1.0 to 7m; for a wall thickness greater than 1.0mm, it is 1.5 to 8m.

B. There are 45 types of hot-rolled (hot-extruded) steel pipes with a diameter of 54 to 480mm and 36 types of wall thickness of 4.5 to 45mm. There are 65 types of cold-drawn (rolled) steel pipes with a diameter of 6 to 200mm and 39 types of wall thickness of 0.5 to 21mm.

C. There shall be no cracks, folds, cracks, cracks, rolling folds, delamination and scar defects on the inner and outer surfaces of the steel pipe. These defects shall be completely removed (except for pipes for mechanical processing). After removal, the wall thickness and outer diameter shall not exceed the negative deviation. Other minor surface defects that do not exceed the allowable negative deviation may not be removed.

D. Allowable depth of straight track: For hot-rolled and hot-extruded steel pipes with a diameter less than or equal to 140mm, it shall not exceed 5% of the nominal wall thickness, and the maximum depth shall not exceed 0.5mm; for cold-drawn (rolled) steel pipes, it shall not exceed 4% of the nominal wall thickness, and the maximum depth shall not exceed 0.3mm.

Types of Stainless Seamless Steel Pipe

Stainless steel seamless pipes can be classified into two categories according to the rolling method. One is hot rolling or hot extrusion and cold drawing. The difference is that one is through high temperature and high pressure casting of stainless steel seamless pipes, and the other is through cold drawing directly on the original basis. In the manufacturing process, it needs to be cooled while manufacturing. According to the different organizational structures of stainless steel, it can be divided into martensitic stainless steel seamless pipes, austenitic stainless steel seamless pipes and austenitic-ferritic stainless steel seamless pipes.

Other types include：

Super-Austenitic steel

Ferritic and Martensitic steel
Duplex steel

Standard of Stainless Steel Seamless Pipe

ASTM A312 Austenitic Stainless Steel Pipes for high-temperature and general corrosive service.
ASTM A213 for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes
ASTM A269 Austenitic Stainless Steel Tubes for General Service

ASTM A270 for Austenitic and Ferritic/Austenitic Stainless Steel Sanitary Tubes

Stainless Steel Seamless Pipe (Cold Drawn, Cold Rolled, Bright) Main Production Standards:

Serial Number	Standard Type	Production Standards
1	European Standard/EN	EN 10216-5, EN 10216-2
2	German Standard/DIN	DIN 17456, DIN 17458
3	American Standard/ASTM/ASME	A213, A269, A511, A789, A790, A335, A376 SA213, SA312, SA789, SA790, SA335, SA376 SB161, SB163, SB167, SB338, SB668, SB677


4	Japanese Standard/JIS	JIS G3459, G3463
5	National Standard/GB	GB/T 14975, T14976, GB13296, GB5310, GB9948

Stainless Seamless Steel Pipe Production Flow Chart

Production steps of stainless steel seamless pipe:

1. Select high-quality 304 and 316L stainless steel raw material billets and perform hollowing, heading, annealing and other operations.

2. After completing the above operations, it is followed by a multi-pass cold drawing (cold rolling) process. The cold rolling of the pipe is carried out on a multi-roll rolling mill, and the stainless steel pipe is rolled in a ring-shaped hole composed of a variable-section circular hole groove and a stationary conical head.

3. After cold rolling, the stainless steel pipe will have a large yield coefficient and is not suitable for expansion and bending. In order to meet the hygienic standards of stainless steel pipes, the cold-rolled pipes also need to be bright annealed, demagnetized, pickled, straightened and other steps.

5. During the pickling process of stainless steel pipes, the pipe fittings can remove oil stains, rust spots, welding spots, oxide layers, free iron and other dirt on the surface of the workpiece while pickling and passivating. The surface becomes uniform silver-white after treatment, while preventing metal from excessive corrosion and hydrogen embrittlement and inhibiting the generation of acid mist.

6. After the above processes, the stainless steel pipe will be polished. The standard number of mesh for the inner and outer walls of the pipe is 400 mesh. The surface finish of the inner and outer surfaces of the polished pipe can reach the mirror standard (that is, the sanitary standard).

7. After polishing, the stainless steel pipe needs to be inspected by a metal flaw detector (or water pressure test) and strictly hand-selected by the steel pipe quality inspector. Only qualified products can be packaged and shipped.

Stainless Seamless Steel Pipe Production Flow Chart

Stainless Steel Seamless Pipe Applications

Stainless steel seamless pipes are widely used for their excellent mechanical properties, corrosion resistance, and ability to withstand high temperatures and high pressures. Some common applications for stainless steel seamless pipes include:

Oil and gas industry: Stainless steel seamless pipes are used in the oil and gas industry to transport fluids such as crude oil, natural gas, and refined oil.

Chemical processing industry: Stainless steel seamless pipes are used in the chemical processing industry to transport corrosive chemicals and corrosive materials.

Power generation industry: Stainless steel seamless pipes are used in power plants to transport steam, condensate, and other fluids.

Food processing industry: Stainless steel seamless pipes are used in the food processing industry to transport fluids such as milk, beer, and other beverages.

Automotive industry: Stainless steel seamless pipes are used in the automotive industry for exhaust systems and other applications that require high temperature and corrosion resistance.