Design, mfg. & tested as per api, 520, 521, 526, 527 standardsmodels comply to "asme sec.viii" of boiler & pressure vessels code.Registered under indian boiler regulation (ibr).Also approved by chief controller of explosives department(ccoe)conventional balance bellows design.Complete teflon (feppfa). Lining for highly corrosive services.Softseat arrangement for tight shut-off.