Factory Acceptance Test (FAT) procedure of Control Valve.

The main purpose of performing the factory acceptance test (FAT) is to check the functionality of each control valve as per agreed and approved documents. It is performed at vendor’s location and on their shop floor.

For example, let us take a pressure control valve (PCV) to carry out the FAT. Basic FAT is examination of it by physical means, checking actuator, body dimensions, name plates, and manufacturer test certificates.

Factory Acceptance Test (FAT) is categorized into three activities:

The PCV System Specification as per datasheet:

1. Tag No. :

•             Manufacture: Name of the manufacturer

•             Actuator Model:

•             Supply actuator:

•             Body Model:

•             Size, Valve Model:

•             Positioner Model:

•             Input Signal:

Reference documents

A list of applicable documents are enclosed along with the FAT procedure. This FAT procedure is provided as information and reference to the customers before conducting the FAT.

Test Equipment

The following is a list of test equipment used for functional test the field instruments. If necessary, other instruments will be added and used.

  • Loop calibrator (4-20mA) • Hart Communicator (375 or 475) 
  • Instrument air (header connection) • Rotameter
  • Pressure Gauge • Block/Needle Valve
  • Flange • Tubing and fitting • Hydro pump

Orientation of witness

All concerned representatives shall be briefed on the operating principles of the pressure control valve (PCV) package before commencing the FAT. The exact FAT schedule shall also be explained to the client project management department (PMC) representatives during this briefing.

Punch list

Any discrepancies found are noted during the tests shall be defined, agreed and recorded in the punch list document.

HYDROSTATIC TEST

Purpose

The Hydrostatic test document describes the test procedure for inspection, examination, and pressure test requirements for metal-to-metal seated, nonmetal-seated, resilient-seated gate, globe, butterfly, ball, check, and plug types of valves.

Performed by using a liquid, the test shall show no leakage, and no permanent deformity under the full test pressure.

Scope

The hydrostatic test for valve test specification referenced on a standard API 598.

Equipment and Materials

  • Hydro test pump (higher capacity) in the order of 100 MPa.
  • Instrument Air.
  • Flange.
  • Connector.
  • Tubing SS
  • Test Fluid; water-soluble oil or corrosion inhibitor.

Operational Procedure

  • Adjust regulator for supply pressure to the positioner
  • After filling a valve inlet chamber with a suitable liquid the valve shall be pressurized as shown in the above figure.
  • Close block valve for feed liquid into the test valve.
  • Input pressure from hydro test pump as per ANSI class.
  • The duration of test pressure shall not be less than 3 minutes before the start of the inspection
  • The temperature of test liquid shall not exceed 100° F or 38°C.
  • After the pressure has reached the specified target, the valve body must have no allowable leakage.
  • Open the block valve for pressure release on the valve.

SEAT LEAK TEST

Purpose

This document describes the method or test procedure for the quantity of fluid passing through a valve when the valve is in the fully closed position with differential pressure and temperature (ANSI Leak Class).

Scope

Seat leak test for valve test specification referenced on ANSI B16.104 standard.

Equipment and Materials

  • Main air supply arrangement for 50 psi.
  • Instrument air to control valve
  • Block / Needle valve
  • Flange
  • Connector
  • Union Tee
  • Tubing and ferrule sets
  • Rotameter

Operational Procedure

  • Prior to testing check the air supply pressure, current connections (loop calibrator) shall be provided.
  • Verify the valve is in a fully closed position
  • Verify inlet pressure must not exceed the maximum Inlet body valve.
  • Slightly open the block valve to the valve body inlet at 50 psig (referenced ANSI B16.104
  • Check rotameter for the actual leak, leakage must not exceed the maximum allowable leak on the datasheet.

STROKE TEST

Purpose

The stroke test procedure describes the method for demonstrating that the actuator has enough force to open and close the valve.

The procedure shall illustrate that no mechanical damage or permanent deformation of valve physical components will occur and that accessories function properly as desired.

Scope

In control valve stroke testing, it travels from a normal position to a fully opened or closed-end position in certain operating steps in percentages 0%, 25%, 50%, 75%, and 100%. Time consumed for total valve travel from close to open vice versa are noted down, it is to be verified with supporting documentation.

Equipment and Materials

  • Air filter regulator (set at 20 psi supply).
  • Loop Calibrator (4 – 20 mA).
  • Connector.
  • Tubing and ferrule set.

Operational Procedure

  • Adjust air supply pressure 20 psig to the positioner.
  • Set loop calibrator to provide current input signal (4-20mA) to the positioner.
  • Verify current Input signal to stroke test (Low Travel, Mid Travel, and High Travel).
  • See the percentage of actual travel (0-100%) to match with the current input signal (4-20mA).
  • Hysteresis test is part of valve performance test (as per purchaser requirement) compared the maximum difference in output value for any single input value during the calibration cycle, excluding errors due to the dead band.

Author: R. Srinivasan Ayyangar.