Hydrotesting of valve

what is the pressure test & duration range for hydrotesting of valve and how we calculate the pressure test range according to valve rating 150# 300# 600#

Why not follow API 598?

This article is meant to give an insight into the testing requirements of two of the most commonly used standards in the valve industry API 598 an API6D , specific to oil and gas projects in the middle east. It is very common to come across situations where the project specifications calls for testing according to one of these standards and the vendor proposes the alternate. In situations like these, it will be of advantage to know the basic testing requirements in both these standards.

Valve Types

API 598 – Valve Inspection & Testing

API 598 covers the inspection, examination, supplementary examination & pressure test requirements for resilient –seated, non-metallic –seated, and metal to metal seated valves of the following type

  • Gate
  • Globe
  • Plug
  • Ball
  • Check
  • Butterfly

API 6D – Specification for Pipeline valves

API 6D specifies the requirements and provides recommendations for the design, manufacturing, testing and documentation of below valve types for application in Pipe Line systems meeting the requirements of petroleum and natural gas industry for pressure ratings less than PN 420

  • Gate
  • Plug
  • Ball
  • Check

The key differences to note here are the industries these specifications are catering to and hence the valve types covered. When API 598 cover general testing requirements for valves manufactured to API 602, API 608, API 609 etc. API 6D specifically caters to valves manufactured for petroleum and natural gas pipe lines.

Type of Tests (Standard Requirements)

TABLE-1 (DN <= 100 and ASME Class <=1500 / DN>4 and ASME Class <=600)

As evident from the table above there is considerable difference in the type of tests required for both the codes and the valves are not completely interchangeable. The requirements are to be checked on case to case based on the type of valve and service conditions.

In addition to the above testing type differences, API 6D also specifies the sequence of tests to be performed and have provided a more detailed procedure for each test.

Test Duration

As noted in the tables above there is a considerable difference in test duration in API 598 & API 6D

Acceptance Criteria

Maximum Allowable Leakage API 598
· Back Seat Test – No visible leakage
· Hydrostatic Shell Test – No visible leakage

Seat test

Maximum Allowable Leakage API 6D

· Back Seat Test – No visible leakage
· Hydrostatic Shell Test – No visible leakage
· Seat Test (Ref. ISO 5208)

o Soft Seated Valves - No visible leakage (Rate A)
o Metal Seated Valves (Liquid)
o 0.1 x DN mm3/s
o 0.0016 x DN dops/S

Like what is stated above there are various differences in the testing and acceptance of these two standards. A decision on acceptance of the valve based on the test criteria other than what is specified should be carefully done considering the above.

4 Likes

thanks and appreciate for sharing knowledgeful info.
pls keep the same in future.

You also may apply FCI70-2 for some valves