A105 Fitting Specifications


ASTM A105 and ASME SA105 covers seamless forged carbon steel piping components for use in pressure systems at ambient and high-temperature service.

Flanges, fittings, valves and various other parts ordered to customer dimension or to industry standards such as MSS, ASME and API specification are included in the scope.

Forgings to this specification are limited to 10,000 lbs.


These components can be welded. Welding procedures must comply with ASME Boiler and Pressure Vessel Code Section IX.

Heat Treatment

Heat treatment is not a mandatory requirement except for flanges above Class 300, flanges of special design where the design pressure or design temperature are not known and for items over 4” NPS and above Class 300. When heat treatment is required, annealing, normalizing, normalize and temper, normalize and quench and tempering shall be the applied methods.


This alloy is forged at between 1,700 degrees Fahrenheit and 2,200 degrees Fahrenheit, followed by quenching and tempering.


Forged parts are allowed to cool to below 1,000 degrees Fahrenheit before reheating to between 1,550 degrees Fahrenheit and 1,700 degrees Fahrenheit. Slow furnace cooling follows.

Chemical Composition

Element Composition %, Note C
Carbon .35 max
Manganese .60-1.05
Phosphorus .035 max
Sulfur .040 max
Silicon .10-35
Copper .40 max, note A
Nickel .40 max, note A
Chromium .30 max, note A,B
Molybdenum .12 max, note A,B
Vanadium .08 max, note A
Note A – The sum of copper, nickel, chromium, molybdenum and vanadium shall not exceed 1.00%
Note B – The sum of chromium and molybdenum shall not exceed .32%
Note C – for each reduction of 0.01% below the specified carbon maximum (.35%), an increase of .06% manganese above the specified maximum (1.05%) will be permitted up to a maximum of 1.65%

Mechanical Properties

Tensile 70 ksi, min
Yield, note A 36 ksi, min
Elongation in 2in, Basic minimum for wall 5/16″ and over, strip test 30%
Hardness 187 HBW max
Note A – Determined by either the 0.2% offset method or the 0.5% extension-under-load method. Other test methods available as listed in A105.

Download the full product catalog.

Hydrostatic Test

Hydrostatic Test shall be conducted by the forging manufacture only when Supplemental S57 of ASTM A961 is specified.

Reference Documents

  • A266/A266M Specification for Carbon Steel Forgings for Pressure Vessel Components
  • A675/A675M Specification for Steel Bars, Carbon, Hot-Wrought, Special Quality, Mechanical Properties
  • A696 Specification for Steel Bars, Carbon, Hot-Wrought or Cold-Finished, Special Quality, for Pressure Piping Components
  • A788/A788M Specification for Steel Forgings, General Requirements
  • A961/A961M Specification for Common Requirements for Steel Flanges, Forged Fittings, Valves, and Parts for Piping Applications
  • MSS Standard – SP 44 Standard for Steel Pipe Line Flanges
  • B16.5 Dimensional Standards for Steel Pipe Flanges and Flanged Fittings
  • B16.9 Wrought Steel Buttwelding Fittings
  • B16.11 Forged Steel Fittings, Socket Weld, and Threaded
  • B16.34 Valves-Flanged, Threaded and Welding End