Valve Pressure Testing: Shell vs Seat Tests & Buyer Checklist

Emerson's inspection overview describes hydrostatic testing of pressure-retaining parts such as bodies and bonnets. ISO 5208's public scope separately identifies pressure-boundary integrity and closure tightness. Use those distinctions to organize the document review, not to copy another manufacturer's procedure or claim its results for a KEHUA model.

API 598 and ISO 5208 are references buyers may encounter in industrial valve inspection requirements. Do not assume a standard applies to every valve or that two standards have identical test requirements. The API source-inspection guide expressly tells inspectors to confirm the purchase-order requirements; its 2015 guidance is background, not a substitute for the contract's current controlled standard.

Ask the supplier to identify the governing product standard, inspection and test standard, edition, project amendments and any proposed deviations. Resolve conflicts before purchase. For a valve offered to a pipeline specification such as API 6D, request its applicable testing scope instead of automatically replacing it with API 598.

A purchasing requirement should identify the test, medium, pressure, duration, temperature where relevant, leakage limit, units and observation or measurement method. Ask for the exact clause or approved project requirement supporting each acceptance criterion. Keep shell leakage observations separate from closure leakage measurements. For a ball valve enquiry, compare the metal-seated floating ball valve with the soft-seated floating ball valve as separate proposals. Ask the supplier to confirm the offered seat materials, test direction and leakage acceptance for each model; neither series name alone defines the acceptance limit.

Do not accept 'zero leakage', 'bubble-tight' or 'tested to standard' as a complete technical specification without the test boundary. Ask which seat arrangement and direction were evaluated, what limit was used and how the result was recorded. Avoid converting a factory acceptance statement into a lifetime or all-service-condition guarantee.

Create a line-item review sheet that links the purchase-order item, valve identification, offered model, size, pressure designation, materials and approved drawing revision. The buyer's goal is to establish which supplied valve or documented batch the record covers; a photograph of a gauge cannot establish this relationship by itself.

Agree the required report contents before production. The checklist below is a proposed procurement format, not a declaration that every field is mandatory under every standard.

Treat each required evidence item as a separate line in the inspection and test plan. A routine shell or closure record should not be used to imply that fire, fugitive-emission, cryogenic, endurance or other project-specific qualification has also been completed. Ask for the applicable record and scope whenever the project requires those claims.

Likewise, a management-system certificate does not identify the test result for the delivered valve. Request the documents relevant to the offered model and the actual order, and compare them with the contract's acceptance matrix.

Use the following template to open the technical discussion. Leave unconfirmed items marked 'to be agreed'; do not choose a pressure, medium or acceptance rate from a generic web table. The supplier and responsible project engineer should return an agreed inspection plan before production.

Start with the relevant KEHUA valve family and identify the exact series, construction and intended duty. Send the service data, requested standard and document checklist with the enquiry so the proposed inspection scope can be reviewed. This article does not establish an inspection rating, leakage class or qualification for every product in the catalogue.