ASTM A193 is a specification for alloy and stainless steel fasteners used in high-temperature or high-pressure environments. It covers the chemical and mechanical requirements for bolts, studbolts , screws, nuts, and other fasteners used in pressure vessels, valves, flanges, and fittings. The standard is issued by the American Society for Testing and Materials (ASTM). The specification includes seven different grades, each with its own chemical composition and mechanical properties. Grade B7 is the most common grade of ASTM A193 and is typically used in fasteners for pressure vessels, valves, flanges, and fittings. Grade B7 bolts are made from a chromium-molybdenum alloy steel and are heat treated to provide increased strength and reliability. The bolts are available in diameters ranging from 1/4 inch to 4 inches and lengths up to 72 inches. what is ASTM A193 Grade B7 ? ASTM A193 Grade B7 is a chromium-molybdenum alloy steel that is used in a variety of high-temperature and hig