| Standard: | ASTM A789 | Grade: | ASTM A789 UNS S31803 |
|---|---|---|---|
| NDT: | HT/UT/ET | Seamless Pipe & Tube Size: | 1/2”to 8′ |
| Outer Diameter: | 6.0- 630 Mm | Schedules: | 10s， 20， 40s， 40， 60， 80s， 80， 100， 120， 140， 160， XXH |
| Application: | Boilers， Superheaters And Heat Exchangers | ||
| High Light: | Boilers Duplex Stainless Steel Tube， Duplex Stainless Steel Tube ASTM A789， UNS S31803 Duplex Stainless Steel Pipe | ||
ASTM A789 UNS S31803 Duplex Stainless Steel Tube for Chemical Process Plant
ASME SA789 S31803 stainless steel tubing provides better pitting and crevice corrosion resistance than 316L or 317L austenitic stainless steel in almost all corrosive media. It also has high corrosion and erosion fatigue properties， as well as lower thermal expansion rates and higher thermal conductivity compared to austenitic stainless steels. The advantage of a duplex structure is that it combines the advantages of ferritic alloys， stress corrosion resistance， crack resistance， and high strength with the ease of manufacture and corrosion resistance of austenitic alloys.
Duplex ASTM A789 S31803 is a nitrogen-enhanced， duplex stainless steel developed specifically to address the common corrosion problems encountered with 300 series stainless steels. "Duplex" describes a family of stainless steels that are neither fully austenitic (e.g.， 304 stainless steel) nor pure ferrite (e.g.， 430 stainless steel). The structure of S31803 duplex stainless steel consists of an austenitic cell surrounded by a continuous ferritic phase. Under annealed conditions， S31803 contains about 40-50% ferrite. Often referred to as the workhorse grade， S31803 is the most widely used grade for duplex stainless steel tubing.
The use of S31803 stainless steel tubing should be limited to temperatures below 600 °F. Prolonged exposure to high temperatures can make S31803 stainless steel brittle.
Chemical Composition
| Grade | C max | Si max | Mn max | P max | S max | Cr | Ni | Mo | N |
| UNS S32750 | 0.030 | 0.8 | 1.2 | 0.030 | 0.015 | 24.0-26.0 | 6.0-8.0 | 3.0-5.0 | 0.24-0.32 |
| UNS S31803 | 0.030 | 1.0 | 2.0 | 0.020 | 0.020 | 21.0-23.0 | 4.5-6.5 | 2.5-3.5 | 0.08-0.20 |
| UNS S31500 | 0.030 | 1.0 | 1.2-2.0 | 0.030 | 0.030 | 18.0-19.0 | 4.5-5.5 | 2.5-3.5 | 0.05-0.10 |
Physical Properties
| Grade | Y.S.MPa min | T.S.Mpa min | Elongation % | Hardness HRC |
| UNS S32750 | 550 | 800 | 15 | 20 |
| UNS S31803 | 450 | 620 | 25 | 20 |
| UNS S31500 | 440 | 630 | 30 | 20 |
Heat Treatment Requirements
| UNS Designation | Temperature | Quench |
| S31803 | 1870-2010 °F [1020-1100°C] | Rapid cooling in air or water |
| S32205 | 1870-2010 °F [1020-1100°C] | Rapid cooling in air or water |
| S31500 | 1800-1900 °F [980-1040°C] | Rapid cooling in air or water |
| S32550 | 1900 °F [1040°C] min. | Rapid cooling in air or water |
| S31200 | 1920-2010 °F [1050-1100°C] | Rapid cooling in water |
| S31260 | 1870-2010 °F [1020-1100°C] | Rapid cooling in water |
| S32001 | 1800-1950 °F [982-1066°C] | Rapid cooling in air or water |
| S32304 | 1700-1920 °F [925-1050°C] | Rapid cooling in air or water |
| S32750 | 1880-2060 °F [1025-1125°C] | Rapid cooling in air or water |
| S32760 | 2010-2085 °F [1100-1140°C] | Rapid cooling in air or water |
| S32950 | 1820-1880 °F [990-1025°C] | Rapid cooling in water |
| S32520 | 1975-2050 °F [1080-1120°C] | Rapid cooling in air or water |
Duplex Stainless Steel Pipe Application
- Chemical processing
- Transport and Storage
- Oil and gas exploration and offshore rigs
- Oil and gas refining
- Marine environments
- Pollution control equipment
- Pulp and paper manufacturing
- Chemical process Plant
S31803 Tubes Ordering Information
Orders for product under this specification should in- clude the following， as required， to describe the desired material adequately:
- Quantity (feet， metres， or number of lengths)
- Name of product (seamless or welded tubes)
- Grade
- Size (outside diameter and average wall thickness， unless minimum wall thickness is specified)
- Length (specific or random)
- Special requirements
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