manufacturing specifications for gate valve (Class 150, 300, 600, 900, 1500)

	Content	Specification
	General design standard	API600
	Pressure-temperature rating	ASME B16.34
	Face to face dimensions	ASME B16.10
	Flange type and dimensions	ASME B16.5
	Butt-welded end	ASME B16.25
	Inspection and test	API598

CONSTRICTION

SEV globe valve adopt OS&Y. B.B. Rotary Rising Stem and Handwheel, which is in accordance with international general standard.

BODY AND BONNET

After being strictly calculated, the design of the body and bonnet possess good performance of strength, rigidity, perfect seal and flowing ability. It makes more reliable for the seal of the packing and more convenient for the replacement of the packing to have assembled backseat onto the bonnet.

Seat and Disc

The flat or cone sealing is used for the connection between the seat and disc. For SEV globe valve in different pressure or specifications, the seat would have the following types:
　　The connection of the seat and the body may either be threaded or welded type.
　　The threaded type seat is easy for disassemble, maintenance and replacement.
　　The seating surface is directly welded on the body.
For stainless steel gate valve, the sealing surface is machined and finished on the body.

Stem and Yoke Sleeve

The thread coordination of the stem and yoke sleeve adopts appropriate fit clearance and special thread remedy to ensure flexibility of the valve's actuation and the valve's self-locking ability. The contact part of the disc and stem is inserted with a piece of hard stainless steel material, so that this part will not deformed by pressing, nor be rusty to effect flexibility of the disc's operation.

Packing and Lantern Ring

The dimension and quantity of the packing conform to the standard to ensure the reliability of sealing. Packing materialsare made of graphite (free of asbestos). The lantern ring may be supplied if the customers require.

Gasket

Connection between body and bonnet shall be Bolted Flange. Gasket of Flange shall be as follows:

Class 150	Flat Gasket
Class 300	Female or Male Gasket
Class 600&larger	Octagon Ring Gasket

The metal spiral wound gasket with inner ring and filling with graphite makes more reliable for the seal of the gasket and excellent capability of disassembling and reassembling.