There are three main types of bonnets for forged steel check valves, namely bolted, welded and self-sealing.
Bolted bonnets are connected by concave and convex surfaces, and can also be connected by rings as required, using stainless steel strips and flexible graphite spiral wound gaskets.
Welded bonnets are welded by threaded sealing, and can also be welded rigidly as required.
Self-sealing bonnets are connected by threaded self-sealing bonnets.