Regal Sales Corporation Manufacture & Supply ASTM A320 Bolts in India, ASTM A320 L7 Stud Bolts (AISI 4140) Specification Covers Alloy and Stainless Steel Bolting in products such as High Pressure Flanges and High Pressure Pipe Fittings to get high temperature or high pressure & corrosion resistant steels durability and service.