Design, mfg. & tested as per api, 520, 521, 526, 527 standards models 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. Soft—seat arrangement for tight shut-off.