API 600 Valve Trim Chart

What is API 600 Standard?

API Standard 600, from the American Petroleum Institute, describes the criteria for valve design/construction and the material/trim designations for steel gate valves. The most recent version of this standard was published in January 2015, effective as of July 15, 2015.

Scope of API 600

API 600 covers bolted bonnet steel gate valves for the petroleum and natural gas industries, specifically where “corrosion, erosion, and other service conditions indicate a need for full port openings, heavy wall sections, and extra large stem diameters.”

Design Specifications of API 600

API 600 specifies design criteria related to the following:

Body wall thickness
Bonnet wall thickness
Body dimensions
Flanged ends
Butt-welding ends
Body seats
Openings
Bonnet dimensions
Bonnet-to-body joints
Gate
Yoke
Stem and stem nut
Packing and packing box
Bolting
Auxiliary connections

What is Valve Trim?

The trim, particularly the mating elements that regulate the stream to the controller’s demands, is at the heart of the control valve. Each process is distinct in its own right, necessitating particular flow control features. Valve trim includes the stem, plug, disc, seating surface, etc. It’s also the plug and seat arrangement’s actual shape. The flow properties of the valve are determined by the shape of the valve plug.

Valve Trim Parts

The valve-specific trim includes the back seat, glands, spacers, guides, bushings, retention pins, and internal springs.

Disc

A disc is the initial valve trim component. The disc is the component that, depending on its position, enables, throttles, or stops the fluid flow. The name of the valve often originates from the type of disc. Examples include gate, ball, plug, and needle valves, which have discs that are the same shape as the name.

A valve disc can be forged, cast, or manufactured. The sealing face of the valve disc is occasionally hardened to improve wear resistance. The disc required a smooth machine surface to reduce friction with a seat; the valve disc is a pressure-maintenance component.

In the closed position, a disc rests against the stationary valve seat. The stem may move via manual or automated actuation.

Seat

The seat provides the disc with a place to set and seal against. A valve may have more than one seat. There is only one seat on a globe valve and a swing-check valve. A gate valve and a ball valve, on the other hand, have two seats, one upstream and the other downstream.

The efficiency of the seal between the valve disc and seat is directly proportional to the seat leakage rate. Valve seats can be permanent or removable rings. Seats on valves are often screwed, welded, or integrally cast or forged, and are toughened through heat treatment or hard facing.

For optimal sealing, the seating area must have a fine surface polish. For non-critical applications, non-metallic seats were utilized in some ball valves and plug valves. Valve manufacturers produce numerous styles of combination valve seats that combine elastomer and metal seats to attain the requisite leak tightness that metal seats alone cannot achieve.

Back Seat

The back seat comprises a shoulder on the stem and a mating surface on the underside of the bonnet. When the stem is entirely open, it forms a seal. It inhibits media leakage into the packing chamber and into the environment. Note: For safety reasons, it is NEVER recommended to change the packing while the valve is under pressure.

Stem

The stem links the handwheel/actuator and the disc. The valve disc moves and positions from the stem movement. The valve stem delivers the required motion to the disc, plug, or ball for the valve’s opening, closing, or setting. The stem connects the valve’s actuator, handwheel, or lever at one end to the disc at the other.

The linear motion of the disc opens or closes the valve in gate and globe valves, whereas the disc rotates to open or close the valve in the plug, ball, and butterfly valves. Stems are typically stainless steel and typically attach to the disc via connections or other mechanical means.

API 600 Valve Trim Number Chart & Service Suitability

Trim	Material	Seat	Disk	Backseat	Stem	Notes
1	410	410	410	410	410
2	304	304	304	304	304
3	F310	310	310	310	310
4	Hard 410	Hard 410	Hard 410	410	410	seats 750BHN Min.
5	Hardfaced	Stellite	Stellite	410	410
5A	Hardfaced	Ni-Cr	Ni-Cr	410	410
6	410 and Cu-Ni	Cu-Ni	410	410	410
7	410 and Hard 410	Hard 410	Hard 410	410	410	seats 750BHN Min.
8	410 and Hardfaced	Stellite	410	410	410
8A	410 and Hardfaced	Ni-Cr	410	410	410
9	Monel	Monel	Monel	Monel	Monel
10	316	316	316	316	316
11	Monel and Hardfaced	Stellite	Monel	Monel	Monel
12	316 and Hardfaced	Stellite	316	316	316
13	Alloy 20	Alloy 20	Alloy 20	Alloy 20	Alloy 20
14	Alloy 20 and Hardfaced	Stellite	Alloy 20	Alloy 20	Alloy 20
15	304 and Hardfaced	Stellite	Stellite	304	304
16	316 and Hardfaced	Stellite	Stellite	316	316
17	347 and Hardfaced	Stellite	Stellite	347	347
18	Alloy 20 and Hardfaced	Stellite	Stellite	Alloy 20	Alloy 20