API 16A Wellhead Drilling Spool for Efficient Fluid Control Systems Product Description The drilling spool is used to connect the blowout preventer assembly, casing head, tubing head, choke and kill manifold, and other related components. This cross is made of high quality low carbon alloy steel, which is overheated, and is suitable for high pressure oil and gas wells with wellhead pressure less than 35MPa. Before delivery, it is inspected according to SY / t5053.1-2000 BOP