ASTM A178 ERW pipe, ASTM A178 Boiler tube

ASTM A178/178M —— Standard Specification for Electric-Resistance-Welded Carbon Steel and Carbon-Manganese Steel Boiler and Superheater Tubes

ASTM A178/178M ERW pipe & tube is to be used in boiler tubes, boiler flues, superheater flues and safe ends. Steel Grades A (low-carbon steel), C (medium-carbon steel), or D (carbon-manganese steel). Manufacturing processes must include heat treatment, welding after cooling. Crush test shall be performed if required by customer.

ASTM A178/A178M standard specifies the technical requirements for resistance welded carbon steel and carbon-manganese steel for boiler and superheater steel pipes. This welding method uses the resistance heating effect generated by the current flowing through the contact surface and adjacent areas of the workpiece to heat it to a molten or plastic state to form a metal bond.

There are four main resistance welding process methods, namely spot welding, seam welding, projection welding, and butt welding. These technologies are widely used to manufacture key components of boilers and superheaters, ensuring the performance and safety of the equipment. In addition, the ASTM A178 standard also covers materials such as seamless pipes and welded austenitic steel pipes. These materials are particularly suitable for use in boilers and superheaters used in high-temperature environments because of their excellent heat resistance and mechanical properties.

What is ASTM A178 Grade A?
ASME SA178A / ASTM A178 Grade A is an ERW (electric resistance welded) low carbon steel boiler tube used in super heaters, water wall panels, heat exchangers, condensers, marine application, refineries, paper pulping, petrochemical applications, pressure vessels, and general engineering applications.

Chemical Composition of ASTM A178 ERW Pipe:

Element %	ASTM A178 Gr A / SA178A	ASTM A178 Gr C / SA178C	ASTM A178 Gr D / SA178D
	Low carbon steel	Medium Carbon Steel	Manganess Steel
C	0.06-0.18	0.35 Max	0.27 Max
Mn	0.27-0.63	0.80 Max	1.00-1.50
P	0.035	0.035	0.030
S	0.035	0.035	0.015
Si	-	-	0.10 Min.

ASTM A178 ERW Pipe Product Analysis:

1. When requested on the purchase order, a product analy- sis shall be made by the manufacturer or supplier from one tube per 100 pieces for sizes over 3 in. [76.2 mm] and one tube per 250 pieces for sizes 3 in. [76.2 mm] and under; or when tubes are identified by heat, one tube per heat shall be analyzed. The chemical composition thus determined shall conform to the requirements specified.

2. If the original test for product analysis fails, retests of two additional lengths of flat-rolled stock or tubes shall be made. Both retests, for the elements in question, shall meet the requirements of the specification; otherwise all remaining material in the heat or lot shall be rejected or, at the option of the producer, each length of flat-rolled stock or tube may be individually tested for acceptance. Lengths of flat- rolled stock or tubes which do not meet the requirements of the specifications shall be rejected.

Mechanical Properties of ASTM A178 ERW Pipe & Tube:

Item	ASTM A178 Gr A / SA178A	ASTM A178 Gr C / SA178C	ASTM A178 Gr D / SA178D
Tensile strength, min, ksi [MPa]	47[325]	60[415]	70[485]
Yield strength, min, ksi [MPa]	26[180]	37[255]	40[275]
Elongation in 2 in. or 50mm, min, %	35	30	30
For longitudinal strip tests a deduction	1.50A	1.50A	1.50A
Each1⁄32-in[0.8mm] decrease in wall thickness below 5⁄16in. [8mm]
From the basic minimum elongation of the following percentage points shall be made

Outside diameter and Wall Thickness Tolerance of ASTM A178 ERW Pipe &Tube

Outside Diameter Tol		Wall thickness Tol
OD < 50	±0.05mm	S < 4mm	±12.5%
OD > 50	±1%	4--20mm	+15/-12.5%
		S≧20mm	±12.5%

ASTM A178 ERW Pipe Manufacture & Heat Treatment
The ASTM A178 Grade D steel shall be killed. ASTM A178 tubes shall be made by electric-resistance welding process. After welding, all tubes shall be heat treated at a temperature of 1650°F [900°C] or higher and followed by cooling in air or in the cooling chamber of a controlled-atmosphere furnace. Cold-drawn tubes shall be heat treated after the final cold-draw pass at a temperature of 1200°F [650°F] or higher.

ASTM A178 ERW Pipe Inspection
ERW pipes made from ASTM A178 steel may be tested or inspected in the following ways covering crush test, flattening test, flange test, tension test, reverse tension test, hydrostatic test, nondestructive electric test, dimension inspection, visual examination, as well as ultrasonic inspection.

ASTM A178 ERW Pipe Application
ASTM A178 tubing is used in boiler, superheater, heat-exchanger and pressure equipment in Petrochemical factory, Refinery factory, sugar mill, power plant, power plant, shipbuilding.

Read more: Welded steel pipe production process or Mechanical Tubing