ASTM A358 TP321 Welded Austenitic Stainless Steel Pipe For high tempersture

YUHONG GROUP deal with stainless steel seamless pipe and tube already more than 33 years, every year sell more than 80000 tons of stainless steel seamless pipe and tube. Our client already cover more than 65 countries. Our stainless steel seamless pipe and tube was width used in Mining, Energy, Petrochemical, Chemical Industry, Food plant, Paper plant, Gas and Fluid Industry etc.

Description

321 stainless steel (uns nos32100) Grade 321 and 347 are the basic austenitic 18/8 steel (Grade 304) stabilised by Titanium (321) or Niobium (347) additions. These grades are used because they are not sensitive to intergranular corrosion after heating within the carbide precipitation range of 425-850°C. Grade 321 is the grade of choice for applications in the temperature range of up to about 900°C, combining high strength, resistance to scaling and phase stability with resistance to subsequent aqueous corrosion.

Grade321H is a modification of 321 with a higher carbon content, to provide improved high temperature strength.
A limitation with 321 is that titanium does not transfer well across a high temperature arc, so is not recommended as a welding consumable. In this case grade 347 is preferred - the niobium performs the same carbide stabilisation task but can be transferred across a welding arc. Grade 347 is therefore the standard consumable for welding 321. Grade 347 is only occasionally used as parent plate material.

Like other austenitic grades, 321 and 347 have excellent forming and welding characteristics, are readily brake or roll formed and have outstanding welding characteristics. Post-weld annealing is not required. They also have excellent toughness, even down to cryogenic temperatures. Grade 321 does not polish well, so is not recommended for decorative applications.

Grade 304L is more readily available in most product forms, and so is generally used in preference to 321 if the requirement is simply for resistance to intergranular corrosion after welding. However 304L has lower hot strength than 321 and so is not the best choice if the requirement is resistance to an operating environment over about 500°C.

Five classes of pipe are covered as follows

Class 1—Pipe shall be double welded by processes employing filler metal in all passes and shall be completely radiographed.

Class 2—Pipe shall be double welded by processes employing filler metal in all passes. No radiography is required.

Class 3—Pipe shall be single welded by processes employing filler metal in all passes and shall be completely radiographed.

Class 4—Same as Class 3 except that the weld pass exposed to the inside pipe surface may be made without the addition of filler metal (see 6.2.2.1 and 6.2.2.2).

Class 5—Pipe shall be double welded by processes employing filler metal in all passes and shall be spot radiographed.

Equivalent Grades

Chemical Composition

Mechanical Properties

Application

Heat Exchanger & Boiler

Oil & Gas Refining

Oil & Gas Pipeline

Petrochemical Industry

Pharmaceutical Industry

Food Industry

Water Treatment

Onshore & Offshore Platform, Ship building

Electric Plant, Sugar Plant, Paper making factory

Others