Valve Magazine - Summer 2011

simulation, the valve is heated at least twice to around 500° F (260° C) during the test sequence. The heating cycles simulate the temperature variances that might be acting on an installed valve. The temperature spikes also provide prototypical movement in the packing due to the expansion and contraction of the materials of construction. It is usually after a thermal cycle that a valve under test will show leakage.

The two schools of thought on the test media also relate into two schools of thought on the test procedures themselves. The International Organization for Standardization (ISO) has FE testing standards as do the American Petroleum Institute (API) and the International Society of Automation (ISA). The ISO standard 15848-1 is currently under revision to make it more user friendly. API is updating its FE packing qualification standard (API RP622) as well creating a new valve FE test standard (API RP 624).

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Table 2. FE Test Specifications Standard Organization ISO 15848-1 ISO (International) ISO 15848-2 ISO (International) API RP622 API (USA) API RP624 API (USA)

ISA-S75.19

FCI-70-2

TA-Luft-VDI 2440

ISA (USA)

FCI (USA)

TA-Luft (Germany)

Notes
Prototype test
Production test
For packing evaluation
Valve standard under
development
For control valves
Primarily control valves
German FE test protocol

Table 3. Fire Test Standards Standard Organization API 607 API (USA) API 6FA API upstream group (USA) API 6FB API upstream group (USA) API 6FC API upstream group (USA) API 6FD API upstream group (USA) ISO 10497 ISO (International)

Notes
Ball valves
Valves
Gaskets
Automatic backseat valves
Check valves
General fire test standard

FIRE TESTING

The most visually exciting of the
extreme valve tests is the fire test—
when you mix high pressure, water and
several gas-fueled “flame throwers”
together, the result is certainly not bor-
ing. Fire testing is used to simulate a
fire in a plant or refinery and determine
how well specific valves and components
will function during that fire and after it
has been extinguished. The procedure
involves pressuring the valve with water
and then focusing several jets of flame
onto the valve. After the test piece has
attained the prescribed temperature, the

valve is doused with jets of water, simulating the firefighting aspect of the process. The leakage rate of the valve or component is then measured and compared with acceptable leakage rate for the test standard.

Fire testing is performed regularly on soft-seated ball valves to determine if they are fire-safe, meaning that, after the initial polymer seal burns away, a secondary metal-to-metal backup seal can still prevent major flow through. Upstream valve manufacturers use a variety of fire-testing standards to confirm the efficacy of the seals in their products to withstand fires at the wellhead.

In today’s marketplace, castings are especially vulnerable to poor workmanship.

RADIOGRAPHY

Today’s newer, low-cost manufacturing sources, combined with a loss in U.S. manufacturing expertise, are creating increased scrutiny on valves and other piping components. Castings are especially vulnerable to poor quality and workmanship. Because of the nature of their potential defects, unaided visual examination is not enough to instill a sense of security with many valve users. For this reason, users often call for additional nondestructive evaluation (NDE).