PESO Approval for Safety Relief Valves: Complete Guide to Requirements & Compliance 

• PESO Approval for Safety Relief Valves is closely associated with the safety requirements applicable to pressure vessels under the Static and Mobile Pressure Vessels (Unfired) Rules, 2016.
• Safety relief valves protect pressure vessels by releasing excess pressure when the vessel approaches an unsafe pressure condition; their design, setting, testing and installation must meet the applicable regulatory requirements.
• Under the SMPV(U) framework, safety relief valves fitted to pressure vessels are subject to testing requirements under Rule 18, with testing and certification involving a recognised Competent Person.

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Introduction

A safety relief valve may be a relatively small component compared with the pressure vessel it protects, but its role is critical.

Imagine an LPG storage vessel, ammonia vessel or industrial-gas installation operating under pressure. If pressure rises beyond the safe design limit, the relief system must respond before the vessel reaches a dangerous condition. A relief valve is one of the key safeguards designed for this purpose.

In India, the regulatory position for safety relief valves depends on where and how the valve is used. For safety relief valves fitted to pressure vessels governed by the Static and Mobile Pressure Vessels (Unfired) Rules, 2016 [SMPV(U) Rules, 2016], PESO requirements are particularly important.

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Why Are Safety Relief Valves Important for Pressure Vessels

A pressure vessel is designed to operate within defined pressure limits. A safety relief valve provides a controlled means of relieving excess pressure when the pressure rises beyond the permitted operating range.

The purpose is straightforward: prevent the vessel from reaching a pressure that could compromise its structural integrity.

The consequences of an inadequate relief system can be severe:

• Vessel rupture
• Gas release
• Fire
• Explosion
• Toxic exposure
• Equipment damage
• Production shutdown
• Environmental incidents
• Regulatory action.

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Which Rules Govern Safety Relief Valve Compliance in India

The principal regulatory framework for safety relief valves installed on pressure vessels is the Static and Mobile Pressure Vessels (Unfired) Rules, 2016.

PESO publishes the SMPV(U) Rules, 2016 on its official website.

The Rules cover the safe storage and transportation of compressed gases and cryogenic liquids in static and mobile pressure vessels.

For safety relief valves, Rule 18 is particularly relevant because it deals with the testing of safety relief valves fitted to pressure vessels. PESO’s own material identifies recognition of Competent Persons under Rule 18 for testing safety relief valves.

PESO also maintains a list of recognised Competent Persons and approved entities under the SMPV(U) framework.

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What Does the SMPV(U) Rules Say About Safety Relief Valves

The regulatory requirements are more detailed than simply saying “install a safety valve.”

The SMPV(U) Rules require pressure vessels to have pressure-relieving devices according to the applicable design code. They also specify requirements concerning the type, setting, capacity and arrangement of relief valves.

Among the important provisions are:

• Relief valves should be spring-loaded.
• Weight-loaded relief valves are not permitted under the stated provision.
• The valve should be designed to prevent inadvertent loading beyond the set pressure.
• The valve must have sufficient relieving capacity.
• Safety relief valves must be set within the prescribed pressure limits.
• The valve should be appropriately marked.
• Connections must be adequately sized for the required discharge.

These requirements demonstrate why a pressure-vessel safety relief valve cannot be selected solely on the basis of pipe size or purchase price.

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What Documents Are Required for PESO Safety Relief Valve Compliance

The exact documentation depends on the application, but a technical compliance file may include:

Product Documents

• Safety relief valve datasheet
• Manufacturer details
• Model number
• Material specifications
• Size
• Pressure rating
• Set pressure
• Discharge capacity
• Gas-service details

Technical Documents

• Valve drawing
• Dimensional drawing
• Sectional drawing
• Design calculations
• Material certificates
• Technical specifications
• Applicable design-code references

Testing Documents

• Test certificate
• Set-pressure test report
• Discharge-capacity test evidence, where applicable
• Inspection report
• Competent Person certificate
• Calibration records

PESO’s current SMPV(U) SOP specifically identifies a Safety Relief Valve certificate issued under Rule 18 as a document used for revalidation of pressure-vessel approvals.

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PESO Approval Process for Safety Relief Valves

The practical compliance process can be understood in stages.

Step 1: Identify the Regulatory Scope

First determine whether the valve is being used with a pressure vessel governed by SMPV(U) Rules, 2016.

Step 2: Review the Vessel

The valve should be assessed against the protected vessel’s:

• Design pressure
• Maximum allowable working pressure
• Capacity
• Stored gas
• Design code
• Operating conditions

Step 3: Review Valve Specifications

Confirm the valve’s:

• Set pressure
• Relieving capacity
• Size
• Material
• Connection
• Temperature range
• Gas compatibility
• Construction

Step 4: Review Technical Drawings

The valve drawing should correspond with the actual product.

Changes in spring, nozzle, orifice, material or setting arrangement should not be made casually after technical approval or testing.

Step 5: Testing

The safety relief valve is tested through the applicable procedure.

PESO recognises Competent Persons for Rule 18 testing.

Step 6: Certification

The required certificate or test documentation is prepared in the applicable format.

PESO’s 2024 SMPV(U) SOP states that certificates relating to safety relief valve testing are issued online within the applicable compliance system.

Step 7: Installation Verification

The valve’s installation should be checked against the pressure-vessel design and applicable requirements.

Step 8: Periodic Testing

Testing does not end with initial installation. The SMPV(U) Rules require safety relief valves to be tested by a Competent Person at least once every year, with records maintained.

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Common Compliance Mistakes

Choosing a Valve Only by Pressure Rating

A valve’s nominal pressure rating alone does not establish that it is suitable.

Set pressure, capacity, temperature, fluid compatibility and installation arrangement also matter.

Ignoring Discharge Capacity

The relief valve must be capable of relieving the pressure adequately.

A small valve with an attractive price is not a substitute for correctly calculated relieving capacity.

Treating Testing as a One-Time Activity

The applicable SMPV(U) provision requires periodic testing, including annual testing by a Competent Person.

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How Diligence Certifications Helps With PESO Compliance

Diligence Certifications provides regulatory support for businesses dealing with pressure vessels, LPG, industrial gases and other PESO-regulated activities.

For businesses working with pressure vessels, our related PESO License for Pressure Vessels guide covers the wider SMPV(U) compliance framework, including vessel documentation, testing, inspection and safety fittings.

Our Static Pressure Vessel License guide also explains the compliance considerations for fixed pressure-vessel installations and safety devices.

For a safety relief valve project, Diligence Certifications can assist with:

• Regulatory applicability assessment
• SMPV(U) compliance review
• Technical-document coordination
• Safety relief valve documentation
• Pressure-vessel document review
• Testing and inspection coordination
• Competent Person coordination
• Application assistance
• PESO query support
• Compliance documentation
• Renewal and revalidation assistance

The objective is to make sure that the valve, pressure vessel and regulatory documents remain technically consistent.

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Conclusion

PESO Approval for Safety Relief Valves should not be viewed as a simple product-documentation exercise. For pressure vessels governed by the SMPV(U) Rules, 2016, relief protection is closely connected with the vessel’s design pressure, operating medium, relieving capacity, installation arrangement and testing requirements.

Rule 18 makes safety relief valve testing an important part of ongoing compliance, while the wider SMPV(U) framework governs pressure-vessel safety, inspection and operation.

For manufacturers, EPC contractors and plant operators, the practical lesson is simple: select the correct valve, establish the correct set pressure and relieving capacity, maintain proper technical documentation, use the applicable inspection/testing route and keep periodic testing records up to date.

PESO’s regulatory framework continues to evolve, including digital certification processes and amendments for specialised pressure-vessel applications. Businesses should therefore verify the latest applicable rules and procedures before commissioning new equipment or renewing existing compliance.

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Frequently Asked Questions