Fire Safe Valves: Ensuring Industrial Safety

Introduction

The petrochemical industry involves complex processes. It uses materials that are flammable and explosive. Valves in these environments need special fire-safe designs.

These designs help the valve keep working after being exposed to fire. Fire tests for valves check their fire resistance. Globally, fire testing for valves in the petrochemical industry is very important.

Test Standards

Different standards exist for fire-safety tests. Key standards include:

• ANSI/API 607: Standard for quarter-turn valves with soft seats.
• API 6FA: Standard for pipeline valves and wellhead equipment.
• API 6FD: Standard for check valves.
• ISO 10497: International standard for fire testing of all valve types.

Test Requirements

General Requirements

The general demands of fire-safety tests are similar. Except for check valves, the test involves mounting the valve stem horizontally on a test pipeline.

The valve is in the closed position. The pipeline and valve cavity are filled with water. The system pressure reaches the standard value.

The gas fuel is ignited. The valve is fully enveloped by fire. The flame temperature around the valve must meet the standard requirements.

The fire is maintained for 30 minutes. During this time, internal and external leakage are checked. Further inspection is done after cooling.

Test Items

Key metrics and operational requirements for fire-safety tests include:

1. Internal Leakage During Fire: Internal leakage through the valve seat under test pressure during the fire. Soft seat valves are prone to leakage as the seat softens or melts due to heat. Metal seats generally have less leakage.
2. External Leakage During Fire: External leakage from flanged connections, threaded connections, and stem seals under test pressure during the fire. Heat-induced deformations can cause leakage.
3. Low-Pressure Test After Cooling: Post-fire cooling test measures internal and external leakage under low-pressure conditions. Large pressure classes (above Class 600) do not require low-pressure tests.
4. Operational Test: Under high-pressure conditions, the valve is operated from fully closed to partially or fully open, measuring external leakage. This test also applies to globe valves and butterfly valves.

Result Evaluation

fire-safety test standards state that passing valves can cover the evaluation of other valves with similar structures. Coverage principles include:

1. Size Coverage: API 6FA and API 6FD cover valves with nominal sizes up to twice that of the tested valve. ANSI/API 607 and ISO 10497 cover valves with nominal sizes up to DN200 (NPS8).
2. Pressure Coverage: Valves can cover the evaluation of other valves with up to twice the tested pressure rating. The highest coverage pressure for API standards is Class 2500 (PN420).
3. Material Coverage: Ferritic, austenitic, and duplex materials can cover valves with similar materials. Specific materials can cover others under recognized conditions.

fire-safe Valve Designs

Importance of fire-safe Designs

fire-safe designs prevent catastrophic failures in the event of a fire. These designs ensure that valves can still operate and control the flow of hazardous materials under extreme conditions. This is especially important in high-risk industries like petrochemicals.

Features of fire-safe Valves

1. Metallic Seats: Designed to withstand high temperatures without melting, ensuring the valve remains sealed.
2. Durable Materials: Use of strong materials that can handle the thermal stress during a fire.
3. Tested to Standards: Valves are tested according to standards like API 607 and ISO 10497 to validate their fire-safety.

FAQs

1. What is the significance of fire-safe valves?
   • fire-safe valves ensure that even during a fire, the valve keeps its sealing and operational capabilities, preventing the spread of fire and hazardous materials.
2. How long is the fire test duration for valves?
   • The standard fire test duration for valves is 30 minutes. The valve is subjected to high temperatures to test its integrity.
3. What are metallic seats in fire-safe valves?
   • Metallic seats in fire-safe valves withstand high temperatures without melting. They ensure the valve remains sealed during a fire.
4. Why are API standards important for valve manufacturers?
   • API standards provide a benchmark for safety and performance. They ensure valves meet stringent requirements for fire resistance and operational integrity.
5. How do high temperatures affect valve performance during a fire?
   • High temperatures can cause soft seats to melt and metallic components to deform. fire-safe valves minimize leakage and maintain functionality despite these challenges.

By adhering to stringent standards and thorough testing, SNBV FLOW can produce reliable fire-safe valves. These valves enhance safety in high-risk industrial environments.