Tie every valve serial to its casting heat, shell test and seat trim.

Valve makers machine castings or forgings, fit seats, stems and packing, and pressure test every unit before it ships to a refinery, a water works or a plant builder. Gate, globe, ball, butterfly and check valves each carry a separate parts list, and a stem for one size is useless on the next class up. A buyer expects the serial to answer which heat, which test and which trim, often years after installation and after the original order clerk has left. That is the job.

Production control for valve plants keeps casting heat, bore machining, assembly torque and bench test results under one serial number, while the order records size, class and trim code. Your bench sheets and heat reports come first, since the serial number has to carry them.

A buyer or distributor sends an enquiry listing size, class, end connection, body material, trim and quantity, and you quote from casting cost, machining, seat parts, assembly and testing. Each rough body arrives stamped with its pour heat, and the foundry sends the chemistry report along with the lot. The store counts them and matches the markings to the purchase order. Only then does a body reach machining. Machining sizes the bore, seat face and flange, and the machinist measures bore and seat angle on the first body of each lot before the rest are cut. Then fitting begins.

Seats are lapped or pressed in. Stems, wedges, discs or balls are fitted, and the gland is packed with the braided graphite ring set that the parts list names for that size and class. Gland bolt torque is noted. Each valve is hydrostatically tested on a shell and seat bench with test pressure and hold time recorded against its serial, and a weeping seat goes back to lapping. A leak at site is expensive. The nameplate is stamped with serial, class and body material, and the valve is crated with its certificate and a packing list that names the lot. Large orders often go in several lots, and the buyer expects every lot to arrive with paperwork that matches its own castings, tests and serial numbers.