API 600 Gate Valve Bonnet

Specifications

Key features

• WCB chemistry, tensile strength and yield strength verified per heat lot and released with EN 10204 3.1 certification, so the bonnet enters your valve with the pressure boundary already documented.
• Stem bore and packing box bored concentric within 0.05 mm in one setup, so the stem runs true through the packing instead of dragging and cutting a leak path.
• Gasket face flatness held within 0.05 mm across the full sealing land, giving uniform bolt load and a joint that stays tight through thermal cycling.
• Wall thickness uniform to +/-0.5 mm through the yoke-to-body transition, removing the local thin section that distorts and cracks when the gland bolts are torqued.
• Backseat face machined square to the stem axis, so the backseat makes metal-to-metal contact and allows repacking under pressure as API 600 intends.
• Bonnet bolt circle drilled and tapped on a CNC index, so studs line up with the body flange without reaming or site fitting.
• Casting, machining, pressure testing and coating carried out in-house under one control plan, so a non-conformance is dispositioned before shipment rather than at your goods-in inspection.

Applications

• Oil and gas gathering, transmission and pipeline gate valves.
• Moreover, Refinery and petrochemical process isolation valves.
• Power plant feedwater, condensate and cooling water gate valves.
• Water and wastewater transmission main valves and pump station isolation.
• Marine and offshore ballast, cargo and fire main valves.
• Chemical and industrial plant utility isolation valves.

Quality & compliance

We produce API 600 gate valve bonnets under IATF 16949 and ISO 9001 process control, with A216 WCB supplied and inspected to the material standard named on your drawing and released with EN 10204 3.1 certification covering chemistry, tensile and yield strength, elongation and heat identity. Shell and backseat tests follow API 598 or ISO 5208 to the pressure, duration and acceptance criteria you specify, and magnetic particle or dye penetrant examination of the gasket face and stem bore is supplied to your acceptance level. Radiographic examination, PPAP and FAIR packages, and full dimensional reports with flatness and concentricity records are available for first articles. Charpy V-notch impact testing to your specified temperature and energy value is available where the service calls for it.

FAQ

Which pressure classes and sizes can you supply?

We cast and machine bonnets for Class 150 through Class 900 gate valves, DN50 to DN600 (2 in to 24 in), in the standard API 600 face-to-face and bonnet joint configurations. If your drawing uses a proprietary bonnet joint. It also uses a special extended yoke or a non-standard bolt circle. It also uses we tool to your drawing rather than to a catalogue pattern.

Do you supply material certification to EN 10204 3.1?

Yes. We release every heat lot with EN 10204 3.1 certification reporting chemistry, tensile strength, yield strength, elongation and heat identity, and results are traceable to the castings supplied. If your specification calls for 3.2 certification with a third party witness, we arrange it against your nominated inspection body.

How do you control stem bore concentricity and gasket face flatness?

The stem bore, packing box and gasket face are machined in one setup from the same datum, held concentric within 0.05 mm and flat within 0.05 mm across the sealing land. We measure flatness and concentricity on a CMM or surface plate per the control plan and recorded on the dimensional report supplied with the first article and on request for production lots.

Can you supply a finished bonnet ready for assembly?

Yes. We can supply as-cast, semi-machined or fully machined bonnets with the stem bore, packing box, backseat, gasket face and bolt holes complete, and pressure tested to API 598 if you want the pressure boundary proven before it reaches your line. Coatings, studs, gaskets and packing are supplied to your specification when required.

What is the minimum order quantity?

We accept prototype and pilot quantities from 20 pieces on a single tooling set and scale to production volumes with multi-cavity or multi-pattern tooling as volume justifies. Tooling is identified, maintained and stored at no charge between releases, so replacement bonnets for the installed base can be produced to the same revision years later.