ASTM A860 is the standard specification for wrought high-strength ferritic steel butt-welding fittings of seamless and electric fusion-welded construction. These pipe fittings shall be furnished in accordance with the dimensions of ASME B16.9(for sizes NPS 14 and smaller) or MSS SP 75(for sizes NPS 16 through NPS 48). They can be further categorized into 6 grades: WPHY 42, WPHY 46, WPHY 52, WPHY 60, WPHY 65, WPHY 70. Pipe fittings manufactured to ASTM A860 are usually used with API 5L line pipes and ASTM A694 high-strength forged flanges in high-pressure gas and oil transmission and distribution systems.

 1. Chemical Composition Requirements of ASTM A860

The Chemical Composition of ASTM A860, %
Carbon	≤0.20*A
Manganese	1.00-1.45
Phosphorus	≤0.030
Sulfur	≤0.010
Silicon	0.15-0.40*B
Nickel	≤0.50*C
Chromium	≤0.30*C
Molybdenum	≤0.25*C
Copper	≤0.35*C
Titanium	≤0.05
Vanadium	≤0.10
Columbium	≤0.04
Vanadium plus Columnium	≤0.12
Aluminum	≤0.06

*The carbon equivalent C.E.=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15 shall not exceed 0.42%.
*B If vacuum carbon deoxidation is used, silicon shall not exceed 0.10% by heat analysis and 0.12% by product analysis.
*C The sum of Ni+Cr+Mo+Cu shall not exceed 1.0%.

2. Mechanical Properties of ASTM A860

ASTM A860/ 860M	Yield Strength, min.		Tensile Strength		Elongation, min.	Cv, avg./min.
Grade	ksi	MPa	ksi	MPa	%	ft*lbs	J
WPHY 42	42	290	60-85	415-585	25	30/25	40/34
WPHY 46	46	315	63-88	435-605	25	30/25	40/34
WPHY 52	52	360	66-91	455-625	25	30/25	40/34
WPHY60	60	415	75-100	515-690	20	30/25	40/34
WPHY 65	65	450	77-102	530-705	20	30/25	40/34
WPHY 70	70	485	80-105	550-725	20	30/25	40/34

*1. The actual yield strength shall not exceed specified minimum by more than 15 ksi [105 MPa].
*2. The elongation values shall be measured on the basis of standard round specimen, or small-size proportional specimen, in 4D.
*3. The size of Charpy V-notch specimens shall be 10×10 mm while the impact-test temperature shall be −50°F[−46°C].
*4. All fittings of ASTM A860 shall have a maximum hardness of 22 HRC(235 HBW).

3. Material, Manufacture, Heat Treatment & Tests

The high-strength pipe fittings of ASTM A860 shall be made from fully killed fine-grain material made by a melting process that is intended to produce rounded, well dispersed, fine sulphide inclusions, that promote good notch toughness, assists in the resistance to hydrogen induced cracking, and for weldability suitable for field welding. The starting raw material may consist of plate, sheet, forgings, bar, seamless and fusion-welded pipes.

All fittings shall be heat treatment by one of the methods of normalizing, quenching, tempering or stress relieving. The regular tests & inspections mainly include radiographic examination, ultrasonic test, Charpy V-Notch test, hardness test, etc. Especially, butt-weld tees manufactured by cold forming process shall be liquid penetrant or magnetic particle examined.

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