Stainless Steel Seamless Pipe
304 / 304L Stainless Steel Seamless Pipe
Steel Grade 304 / 304L | UNS S30400 / UNS S30403 | 1.4301 / 1.4307
These types of steel are some of the most regularly specified and have come to represent the embodiment of the basic stainless product. They are part of the 300 Series of steels (as defined in SAE specifications) which covers a range of austenitic chromium-nickel alloys. They are also known as 18/8 stainless due to their chemical composition which includes approximately 18% chromium and 8% nickel by weight. The steels are easy to form, weld, and fabricate and their resistance to corrosion from, amongst other things, acids naturally contained in food has resulted in them being used widely in the food and drink processing industries.
Type 304 and Type 304L have very similar chemical and mechanical properties and are often included on a single material test certificate when the actual properties of a stainless steel plate meet the criteria of both types. This is a very common occurrence. Type 304L is a variation of Type 304 and has a lower carbon content which improves weldability and lowers the risk of reduced corrosion resistance around the weld. Type 304L also has a slightly lower yield and tensile strength than Type 304.
As with most steel plate products a number of different designations are used for these steels. The most common are:
•Type 304 1.4301 (EN Steel Number) S30400 (UNS)
•Type 304L 1.4307 (EN Steel Number) S30403 (UNS)
Typical industrial sectors:
•Food Processing
•Chemical Industry
•Brewing
•Pharmaceuticals
•Petrochemicals
Typical product applications:
•Heat Exchangers
•Pipelines
•Pressure Vessels
•Flanges and fittings
•Valves
•Condensers.
316 / 316L Stainless Steel Seamless Pipe
Grade 316 / 316L | UNS S31600 / UNS S31603 | 1.4401 / 1.4404
These steels are the second most regularly specified stainless steels after Type 304 and are part of the SAE defined 300 Series which encompasses a range of austenitic chromium-nickel alloys. Austenitic stainless steels like Type 316 are widely available, have good general corrosion resistance, good cryogenic toughness, and excellent formability and weldability.
Type 316 has 2-3% Molybdenum included in its chemical composition which prevents specific forms of corrosion and generally enhances its corrosion resistance. Type 316 is often referred to as “marine grade” stainless due to its increased resistance to chloride corrosion compared to Type 304 making it a very suitable material for use in salt water environments.
Type 316L is a variant of Type 316 and differs by having a lower Carbon content as well as slightly lower yield and tensile strengths. Type 316L offers improved weldability and also reduces the possibility of lower corrosion resistance around welded areas.
As with most steel plate products a number of different designations are used for these steels. The most common are:
•Type 316 1.4401 (EN Steel Number) S31600 (UNS)
•Type 316L 1.4404 (EN Steel Number) S31603 (UNS)
Typical industrial sectors:
•Brewing
•Chemical Industry
•Dairy
•Food processing
•Marine equipment
•Petrochemicals
•Pharmaceuticals
Typical product applications:
•Condensers
•Heat Exchangers
•Filters
•Pressure Vessels
•Valves
•Flanges and Fittings
321 / 321H Stainless Steel Seamless Pipe
Grade 321 / 321H | UNS S32100 / UNS S32109 | 1.454 / 1.4878
Characterised by its good oxidation resistance up to 1600F and its superior resistance to polythionic stress corrosion cracking 321 Stainless is an alloy that offers outstanding performance at a competitive price.
Alloy 321 stainless is a titanium stabilized grade commonly used for service in the 1000-1600°F temperature range.
For service temperatures up to about 1600°F, a stabilizing treatment at 1550-1650°F, air cool, may be used to provide optimum resistance to intergranular corrosion and to polythionic acid stress corrosion cracking. 321 stainless is readily welded by all common methods including submerged arc. Appropriate weld fillers are AWS ER347 bare wire and E347 covered electrodes.
321 stainless is similar in machinability to 304 stainless steel. It has a machinability rating of 45% relative to AISI B1112.
Features of Alloy 321
•Oxidation resistant to 1600°F
•Stabilized against weld heat affected zone (HAZ) intergranular corrosion
•Resists polythionic acid stress corrosion cracking
As with most steel plate products a number of different designations are used for these steels. The most common are:
•Type 321 1.4541 (EN Steel Number) S32100 (UNS)
•Type 321H 1.4878 (EN Steel Number) S32109 (UNS)
Typical industrial sectors:
Aircraft piston engine manifolds
Expansion joints
Thermal oxidizers
Refinery equipment
High temperature chemical process equipment
310S Stainless Steel Seamless Pipe
Grade 310S | UNS S31008 | 1.4845
Alloy 310S displays excellent resistance to oxidation under mildly cyclic conditions to 1100°C. Due to its high chromium and medium nickel content, 310S has good resistance to sulfidation and other forms of corrosion.
Alloy 310S is widely used in moderately carburizing atmospheres such as those encountered in petrochemical environments. 310S is not suggested for the severe thermal shock of repeated liquid quenching.
310S is often used at cryogenic temperatures, with excellent toughness to -268°C and low magnetic permeability. 310S has a machinability rating of 42% relative to AISI B1112 steel.
Features of Alloy 310S
• Oxidation resistance to 2000°F
• Moderate strength at high temperature
• Resistance to hot corrosion
Strength and toughness at cryogenic temperatures
As with most steel plate products a number of different designations are used for these steels. The most common are:
• Type 310S 1.4845 (EN Steel Number) S31008 (UNS)
Typical industrial sectors:
Flare tips
• Fluidized bed coal combustors
• Radiant tubes
• Tube hangers for petroleum refining and steam boilers
• Coal gasifier internal components
• Thermowells
• Refractory anchor bolts
• Burners, combustion chambers
• Retorts, muffles, annealing covers
• Food processing equipment
• Cryogenic structures
317L Stainless Steel Seamless Pipe
Grade 317L | UNS S31703 | 1.4438
Alloy 317L is a molybdenum containing, low carbon austenitic stainless steel with increased additions of chromium, nickel, and molybdenum for better corrosion resistance and increased resistance to chemical attack for sulfurous, acetic, formic, citric, and tartaric acids.
Due to its low carbon content, 317L also provides resistance to sensitization when welded and higher creep, stress to rupture, and tensile strength at elevated temperatures.
It is non-magnetic in the annealed condition but may become slightly magnetic after welding.
Alloy 317L is commonly used to handle sulfur, pulp liquor, acid dyestuffs, acetylating and nitrating mixtures, bleaching solutions, severe coal and oil, and many chemical compounds.
Corrosion Resistance
•Demonstrates superior corrosion resistance in difficult environments including a wide range of chemicals, especially in acidic chloride environments
•Excellent resistance in applications where contamination is desired to be kept to a minimum
•Low carbon content allows 317L to be highly resistant to intergranular corrosion
•Combats the tendency to pit when in contact with phosphorus acids, chlorides, bromides, and iodides
Heat Resistance
•All chromium-nickel-molybdenum steels all have excellent resistance to oxidation
•Demonstrates a low rate of scaling in ordinary atmospheres at temperatures up to 1600-1650°F (871-899°C).
As with most steel plate products a number of different designations are used for these steels. The most common are:
•Type 317L 1.443 (EN Steel Number) S31703 (UNS)
Typical industrial sectors:
•Paper and pulp handling equipment
•Chemical and petrochemical processing equipment
•Condensers in fossil and nuclear fueled power generation stations
•Food processing equipment
•Textile equipment
347/H Stainless Steel Seamless Pipe
Grade 347 | UNS S34700 | 1.4550
Type 347 stainless steel has slightly improved corrosion resistance over type 321 stainless steel in strongly oxidizing environments.
Type 347 is stabilized with columbium, it is preferable for aqueous and low temperature environments due to its good resistance to intergranular attack.
Both 347 and 321 offer good resistance to polythionic acid stress corrosion cracking, encountered in oil refineries.
The high temperature oxidation resistance of 347 is similar to that of 304 stainless steel. Useful to 1500°F.
Often in many product forms, the grain size and carbon content can meet both the 347S and 347H requirements.
Appropriate weld fillers are AWS ER347 bare wire and E347 covered electrodes.
Features
•Good creep strength up to 1500°F
•Maintains good corrosion resistance in applications where the temperature is between 800°F and 1500°F.
•Good resistance to intergranular corrosion in the as welded condition.
As with most steel plate products a number of different designations are used for these steels. The most common are:
•Type 347 1.4550 (EN Steel Number) S34700 (UNS)
Typical industrial sectors:
•Oil Refineries
•Fluid catalytic cracking units (FCC)
•Hanger rods
•Recuperator tube sheets, shell, supports
•Especially where temperatures exceed 550°F and resistance to sulfidation is needed
•Fired heater tubes
•Distributor trays and thermowells
•Equipment in and around reactors (good resistance to polythionic acid)
904L Stainless Steel Seamless Pipe
Grade 904L | UNS NO8904 | 1.4539
Alloy 904L (UNS N08904) is a super austenitic stainless steel that is designed for moderate to high corrosion resistance in a wide range of process environments.
The combination of high chromium and nickel content, coupled with additions of molybdenum and copper, assures good to excellent corrosion resistance.
With its highly alloyed chemistry , 25% nickel and 4.5% molybdenum, 904L provides good chloride stress corrosion cracking resistance, pitting and general corrosion resistance superior to 316L and 317L molybdenum enhanced stainless steels.
Alloy 904L was originally developed to withstand environments containing dilute sulphuric acid.
It also offers good resistance to other inorganic acids such as hot phosphoric acid as well as most organic acids.
Applications
• Air Pollution Control — scrubbers for coal-fired power plants
• Chemical Processing — process equipment for the production of sulphuric, phosphoric, inorganic and organic acids and the production of phosphate-based fertilizers
• Metallurgical Processing — pickling equipment using sulphuric acid
• Oil and Gas Production —offshore process equipment
• Pharmaceutical Industry — process equipment
• Pulp and Paper — processing equipment
• Seawater and Brackish Water — condensers, heat exchangers and piping systems