Stainless Steel Pipe Fittings

Stainless Steel Alloy 316 UNS S31600 By yaang.com

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Stainless Steel Alloy 316 UNS S31600 By yaang.com

Stainless Steel 316 is molybdenum-bearing austenitic stainless steel. The higher nickel and molybdenum content in this grade allows it to demonstrate better overall corrosion resistant properties than 304, especially with regard to pitting and crevice corrosion in chloride environments. In addition, Stainless Steel Alloy 316 provides excellent elevated temperature tensile, creep and stress-rupture strengths, as well as outstanding formability and weldability. Stainless Steel Alloy 316 is immune from sensitization; therefore, it is very frequently used in heavy gauge welded components.

CHEMISTRY RANGE, %

  C Si Mn Ni Cr Mo Cu N P S
Min     1.25 10.0 16.0 2.0        
Max 0.08* 1.0 2.0 14.0 18.0 3.0 0.75 0.1 0.040 0.03

*L limits Carbon to .03% maximum

Corrosion Resistance

Excellent in a range of atmospheric environments and many corrosive media – generally more resistant than 304. Subject to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above about 60°C. Considered resistant to potable water with up to about 1000mg/L chlorides at ambient temperatures, reducing to about 500mg/L at 60°C.

Stainless Steel Alloy 316 is usually regarded as the standard “marine grade stainless steel”, but it is not resistant to warm sea water. In many marine environments 316 does exhibit surface corrosion, usually visible as brown staining. This is particularly associated with crevices and rough surface finish.

Heat Resistance

Good oxidation resistance in intermittent service to 870°C and in continuous service to 925°C. Continuous use of Stainless Steel Alloy 316 in the 425-860°C range is not recommended if subsequent aqueous corrosion resistance is important. Grade 316L is more resistant to carbide precipitation and can be used in the above temperature range. Grade 316H has higher strength at elevated temperatures and is sometimes used for structural and pressure-containing applications at temperatures above about 500°C.

Heat Treatment

Solution Treatment (Annealing) – Heat to 1010-1120°C and cool rapidly. These grades cannot be hardened by thermal treatment.

Welding

Excellent weldability by all standard fusion methods, both with and without filler metals. AS 1554.6 pre-qualifies welding of Stainless Steel Alloy 316 with Grade 316 and 316L with Grade 316L rods or electrodes (or their high silicon equivalents). Heavy welded sections in Grade 316 require post-weld annealing for maximum corrosion resistance. This is not required for 316L. Grade 316Ti may also be used as an alternative to 316 for heavy section welding.

Machining

A “Ugima” improved machinability version of grade 316 is available in round and hollow bar products. This machines significantly better than standard Stainless Steel Alloy 316 or 316L, giving higher machining rates and lower tool wear in many operations.

Dual Certification

It is common for Stainless Steel Alloy 316 and 316L to be stocked in “Dual Certified” form – mainly in plate and pipe. These items have chemical and mechanical properties complying with both 316 and 316L specifications. Such dual certified product does not meet 316H specification and may be unacceptable for high temperature applications.

Applications

Typical applications include:

Chemical Process Industry:
Organic and Fatty Acids, Chemical containers, Chemical transport, Heat Exchangers
Marine Industry and Shipbuilding:
Stainless Steel 316 Pipes, Stainless Steel 316 Flanges, Stainless Steel 316 Valves, Stainless Steel 316 Pipe Fittings, Marine architechture
Mining Industry:
Woven screens

Oil and Gas Industry:

Stainless Steel 316 Pipes, Stainless Steel 316 Valves, Stainless Steel 316 Flanges, Heat Exchangers

Stainless steel 316 Features
Low carbon version of 316
Immune from grain boundary sensitisation
Higher resistance to pitting corrosion and crevice corrosion in seawater than 304 stainless steel
Excellent ductility and impact strength at both ambient and sub-zero temperatures
Non-magnetic
Excellent forming and welding characteristics
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)

Article Categories:
Stainless Steel

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