Comprehensive introduction to ASTM A178 ERW pipe

ASTM A178 ERW (Electric Resistance Welded) steel pipe is a type of electric resistance welded pipe produced according to the American Society for Testing and Materials (ASTM) standard A178. This type of steel pipe is mainly used in the manufacture of boilers, superheaters and heat exchangers. The ASTM A178 standard covers steel pipes made of carbon steel and carbon manganese steel with minimum wall thickness requirements and suitable for high temperature and high pressure environments. This blog is a comprehensive introduction to ASTM A178 ERW pipe.

Chemical Composition of ASTM A178 ERW Pipe:

ASTM A178 ERW Pipe Product Analysis:

When specified in the purchase order, a product analysis shall be conducted by the manufacturer or supplier. For pipes with sizes over 3 in. (76.2 mm), one tube shall be tested for every 100 pieces; for sizes 3 in. (76.2 mm) and under, one tube shall be tested for every 250 pieces. If tubes are identified by heat, one tube per heat shall be analyzed. The determined chemical composition must meet the specified requirements.

If the initial product analysis test fails, two additional lengths of flat-rolled stock or tubes shall be retested. Both retests, for the elements in question, must comply with the specification requirements. Otherwise, all remaining material from the heat or lot shall be rejected. Alternatively, the manufacturer may opt to individually test each length of flat-rolled stock or tube for acceptance. Any lengths of flat-rolled stock or tubes that do not meet the specification requirements shall be rejected.

Mechanical Properties of ASTM A178 ERW Pipe:

Outside diameter and Wall Thickness Tolerance of ASTM A178 ERW Pipe

Manufacturing and Heat Treatment of ASTM A178 ERW Pipe

Steel for ASTM A178 Grade D must be killed to ensure uniformity and ductility. The ERW pipes are manufactured using the electric-resistance welding (ERW) method, which fuses the edges of the steel strip together under high frequency to form a solid seam. Post-welding, it is imperative that all pipes undergo a heat treatment process at temperatures reaching or exceeding 1650°F (900°C). This is followed by air cooling or cooling within a controlled-atmosphere furnace's chamber to reduce internal stresses and refine the material's microstructure. For cold-drawn varieties, a heat treatment is also mandatory after the final drawing stage, at temperatures not lower than 1200°F (650°C).

Inspection of ASTM A178 ERW Pipe

The quality assurance of ASTM A178 ERW pipes involves a comprehensive inspection regime that includes a variety of tests. These tests are designed to evaluate the pipe's structural integrity and performance under different conditions. The inspections may encompass crush tests, flattening tests, flange tests, tension tests, reverse tension tests, hydrostatic tests, nondestructive electric tests, dimensional inspections, visual examinations, and ultrasonic inspections to ensure the pipes meet the stringent requirements of the ASTM A178 standard.

Applications of ASTM A178 ERW Pipe

ASTM A178 ERW tubing finds extensive applications across various industries due to its high strength and reliability. It is commonly utilized in critical components of boilers, superheaters, and heat exchangers. These tubes are also found in pressure equipment within petrochemical plants, refineries, sugar mills, and power generation facilities, including both land-based and marine applications. The robust nature of ASTM A178 tubing makes it a preferred choice for applications where high pressures and temperatures are encountered.