PESO Approval for MDI Storage: Complete Compliance Guide

• PESO Approval for MDI Storage depends on the type of MDI, how it is stored, the pressure levels, the equipment used and the rules that apply to the setup.

• For storage that uses pressure vessels or other activities covered by PESO rules the person applying must show that everything meets the standards. This includes plans, details, tests, safety measures and checks.

• Before spending money on an MDI storage system companies need to find out which PESO process is needed, thinking that every MDI tank always needs the same permit.

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Introduction

A company that makes polyurethane got in touch with a compliance consultant after they had already planned their MDI storage system. They had decided on the tank size, started buying pipes and were doing construction work. It was then that they asked a very basic question: Does our MDI storage system need approval from PESO and if so what kind of approval do we need?

This question is really important even if it does not seem like it at first.

MDI, which is short for diphenyl diisocyanate, is used a lot in making polyurethane, insulation, coatings, adhesives and similar things. Depending on the type and how it is made MDI can be a liquid or thick liquid. For example polymeric MDI is. Used as a liquid.

A lot of businesses make a mistake when they think that getting PESO approval for storing MDI is about registering a product.. Peso rules are actually more about what you are doing, the equipment you use, how you store things and what category it falls under.

PESO is in charge of keeping people safe when it comes to things like petroleum, explosives, compressed gases and certain ways of storing and using pressure vessels. They make sure people follow rules like the Static and Mobile Pressure Vessels Rules from 2016, which are often called the SMPV Rules.

So the right way to do things is to figure out which rules apply to you and then you can start filling out forms. You have to understand the rules before you can follow them. This is why it is so important to think about PESO approval for MDI storage, in this way.

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What Is PESO Approval for MDI Storage?

PESO Approval for MDI Storage is about getting the permission from the Petroleum and Explosives Safety Organisation. This is necessary when an MDI storage installation is under the control of PESO.

It is very important to remember that not all MDI storage tanks need a PESO licence. We have to look at the material, the tank, the pressure, the design and the rules that apply.The reason for this is that MDI is not the same as LPG or CNG or other gases that are compressed.

For example there are rules called the SMPV(U) Rules that deal with compressed gases and vessels that can handle pressure. The official procedure of PESO says that after checking the plans and details they can give approval or a licence if the place meets the requirements. They also check the place after giving the licence before it can start working.

So if an MDI project uses equipment that is covered by the rules for pressure vessels it is very important that this equipment meets the requirements. PESO Approval for MDI Storage is crucial in this case and PESO Approval for MDI Storage requires consideration of the equipment used.

To really get what is required, think about PESO compliance, like a chain.

It has parts: the material, how it is stored in the vessel, the pressure and temperature, how it is installed, the safety systems, the rules that apply and the approval or licence.

If one of these parts changes the whole process of following the rules may also change.

So a big tank to store MDI in bulk storing MDI in packages and a special installation that can handle pressure should not be seen as the same when it comes to PESO compliance.

Each of these PESO compliance cases is different. Needs to be treated that way.

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Does MDI Storage Always Require PESO Approval?

To really get what is required, think about PESO compliance, like a chain.

It has parts: the material, how it is stored in the vessel, the pressure and temperature, how it is installed, the safety systems, the rules that apply and the approval or licence.

If one of these parts changes the whole process of following the rules may also change.

So a big tank to store MDI in bulk storing MDI in packages and a special installation that can handle pressure should not be seen as the same when it comes to PESO compliance.

Each of these PESO compliance cases is different. Needs to be treated that way.

Why this assessment should happen before tank fabrication

A storage tank is not something a company should change after it is put in place just because a rule-maker has said something is wrong.A change in:

• tank size,
• design pressure,
• material used,
• nozzle setup,
• safety system,
• heating system,
• insulation,
• pipework,
• base,
• tank position or
• safety space

can impact engineering and rules paperwork.This is why getting PESO Approval for MDI Storage should be thought about during the planning of the project.

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Which PESO Rules Can Apply to MDI Storage?

The legal way to do things is different for each installation.. One thing to look at is the Static and Mobile Pressure Vessels (Unfired) Rules, 2016.

PESO publishes the SMPV(U) Rules, 2016. They have a special procedure for getting approvals and licences under these rules.

These rules and procedures are really important when you have a storage system that uses pressure vessels or compressed gases.

The procedure that PESO has says that they look at the applications and the plans that people submit. If they think it is safe to store things according to the rules they might give approval or a licence. Only if certain conditions are met.

There are rules to think about too.Depending on the project businesses might need to look at laws or rules.These can include:

• Factories and occupational safety requirements
• Fire department requirements
• Environmental and hazardous chemical requirements
• Local authority approvals
• Building and land-use permissions
• Emergency response requirements
• Pollution-control requirements
• Applicable chemical handling standards

The thing to remember is that getting approval from PESO does not mean you do not need to get other approvals that are required by law. PESO approval is one part of the process and you still need to follow all the other rules and regulations that apply to Static and Mobile Pressure Vessels (Unfired) and other things.

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MDI Storage Systems Commonly Seen in Industry

A compliance assessment should cover the actual storage configuration rather than relying on a generic tank description.

Bulk MDI storage tanks

Large manufacturing plants may use dedicated bulk storage tanks for continuous polyurethane production.

The tank may include:

• Insulation
• Heating arrangements
• Temperature monitoring
• Nitrogen blanketing
• Pressure monitoring
• Level indication
• Transfer pumps
• Dedicated pipelines
• Isolation valves
• Vent arrangements
• Emergency systems

Whether PESO approval applies depends on the technical and regulatory characteristics of the installation.

MDI day tanks

A day tank may be used to feed a production line from the main storage area.

Although its capacity is smaller, it should not be ignored from a compliance perspective. The operating pressure, connected piping and design of the vessel still need technical assessment.

MDI storage in imported equipment

Imported process equipment can create another compliance issue.

A foreign supplier may provide a tank according to an international design code. That does not automatically mean the installation satisfies Indian regulatory requirements.

The engineering team should establish:

1. What standard the vessel was designed to;
2. What material was used;
3. What pressure and temperature limits apply;
4. What inspection and testing records are available;
5. Whether the vessel falls under the applicable Indian regulatory framework; and
6. What additional approval or inspection is required before operation.

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Key Documents Required for PESO Approval for MDI Storage

There is no one list of documents that works for every MDI installation. What you need depends on how you get approval.However a project file can have types of documents.Company and site documents are part of this.

Some common documents are:

Certificate of incorporation or business registration

• PAN
• GST registration
• Authorisation letter
• Proof of ownership or lease
• Site ownership documents
• Factory details
• Site location information
• Previous approval documents if you need them

Technical documents are also important.

These are often the important part of a complex application.Depending on the installation you may need:

• General Arrangement drawing
• Tank drawing
• Vessel design details
• Design calculations
• Material specifications
• Welding documentation
• Pressure-test records
• Inspection reports
• Safety-device details
• Valve specifications
• Piping drawings
• Process flow diagrams
• Instrumentation details
• Relief-system information

Safety documentation

The project may also need things like:

• Fire safety arrangements
• Emergency response plan
• Safety procedures
• Operating procedures
• Maintenance procedures
• Hazard identification documents
• SDS for MDI
• PPE requirements
• Spill-response arrangements
• Emergency shutdown philosophy

You should finalize the documents you need after you determine the route, for MDI approval..

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Technical Requirements for an MDI Storage Facility

A technically sound MDI storage system should be designed around both chemical compatibility and mechanical safety.

Tank material and compatibility

The tank construction material must be suitable for the stored MDI grade and operating conditions.

The compatibility assessment should consider:

• Chemical composition
• Temperature
• Pressure
• Corrosion considerations
• Moisture exposure
• Product contamination
• Cleaning requirements

MDI reacts with water, making moisture management an important operational consideration.

Temperature control

Some MDI grades have melting or freezing characteristics that require controlled storage temperature.

For example, pure 4,4′-MDI has a melting range around 39-43°C according to international chemical safety information.

This means the storage design may require heating or temperature management depending on the grade.

The heating system itself must be appropriately designed. A temperature-control failure can affect product quality and process continuity even when it does not create the same hazard profile as a flammable petroleum tank.

Pressure control

If the storage system operates under pressure or uses pressurisation, pressure control becomes a major engineering consideration.

The design should account for:

• Operating pressure
• Design pressure
• Pressure relief
• Nitrogen blanketing, where used
• Vent arrangements
• Instrumentation
• Isolation
• Emergency conditions

Where the vessel falls within the SMPV(U) regulatory scope, these aspects become particularly important to the PESO assessment.

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PESO Inspection for MDI Storage

A common misconception is that regulatory approval ends once the online application is submitted.

It does not.

PESO’s published SMPV(U) SOP provides for inspection of the premises or vehicle after approval to verify conformity with the Act and rules. Where deficiencies are identified, the licensing authority can direct rectification or communicate reasons for non-endorsement.

For a storage installation, inspection readiness should therefore be treated as a project milestone.

What should be checked before inspection?

The applicant should verify that:

• The installed tank matches approved drawings.
• Safety devices are installed as specified.
• Valves and instruments are correctly fitted.
• Piping corresponds with the submitted arrangement.
• Required test certificates are available.
• Tank identification is clear.
• Emergency arrangements are in place.
• Fire and safety equipment are accessible.
• Operating procedures are available.
• Personnel understand the system.
• Any required statutory NOCs are available.

A simple rule is useful here:

Never invite inspection for a facility that exists only on paper.

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PESO Approval for MDI Storage: Step-by-Step Process

Step 1: Determine regulatory applicability

Start by identifying the MDI product and storage configuration.Do not start with the assumption that a particular PESO licence’s mandatory.

Step 2: Review the storage design

Evaluate the tank, pressure conditions, piping, instrumentation, safety systems and site arrangement.

Step 3: Identify the PESO route

If the installation falls under the relevant PESO-administered framework, determine the appropriate application and licence category.PESO provides SOPs for approvals and licences under the SMPV(U) Rules, 2016.

Step 4: Prepare technical drawings

Drawings should accurately represent the proposed or existing installation.A mismatch between drawing and actual site is one of the ways to create inspection problems.

Step 5: Compile technical certificates

Collect vessel documentation, material certificates, inspection reports, test certificates and other technical records applicable to the installation.

Step 6: Submit the application

Applications are processed through the PESO system and reviewed by the competent authority.

Step 7: Technical scrutiny

The authority may examine the submitted specifications, drawings, calculations and supporting documents.

Step 8: Address observations

If the authority raises queries responses should be technically precise and supported by documentation.

Step 9: Site inspection

Where applicable the site is inspected for conformity.

Step 10: approval/licence and ongoing compliance

Once the requirements are satisfied the applicable approval or licence process is completed.PESO also states that licences under the SMPV(U) Rules must be renewed before expiry according to the applicable provisions.

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Common Mistakes in MDI Storage Projects

When you are working on MDI storage projects one thing you should not do is assume every chemical tank needs PESO approval.This can create a lot of work and it can send your project towards the wrong regulatory route.MDI storage projects are not the same as LPG projects.MDI and LPG have physical and hazard characteristics.So the storage compliance for MDI should not be copied from LPG projects.

Here are some other common mistakes people make:

• Buying the tank first. Checking compliance later.

This can become very expensive if the selected vessel or configuration does not fit the regulatory requirements for MDI storage projects.

• Ignoring imported vessel documentation.

A foreign certificate is useful. You need to check if it is acceptable under Indian regulatory requirements for MDI storage projects.

• Preparing drawings after installation.

Engineering drawings for MDI storage projects should reflect the compliance strategy from the beginning.

• Treating fire NOC as PESO approval for MDI storage projects.

A Fire NOC and a PESO approval serve purposes.One does not automatically substitute for the other in MDI storage projects.

• Neglecting modification control in MDI storage projects.

A tank may be compliant when it is approved. Later it may be modified through changes in capacity, location, piping, product, pressure, safety devices, ownership or operational configuration, for MDI storage projects.

These changes should be reviewed for their implications before they are implemented in MDI storage projects.

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How Long Does PESO Approval for MDI Storage Take?

The processing period depends on the type of approval, quality of documentation, complexity of the facility, authority observations and inspection readiness.

PESO’s current procedures should be checked rather than relying on an old generic timeline.

One useful point from the regulator is that it has specifically issued guidance intended to minimise discrepancy letters and address processing timelines.

In practical terms, businesses can reduce avoidable delay by completing the technical package before filing.

The fastest application is not necessarily the one submitted first. It is usually the one submitted with fewer technical gaps.

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Is PESO Approval Renewable?

Where a PESO licence is issued under a regulatory framework that provides for renewal, the licence must be renewed according to the applicable provisions.

PESO’s SMPV(U) SOP specifically states that licences granted under the rules are to be renewed before their expiry under Rule 55.

Companies should therefore maintain a compliance calendar rather than waiting until the licence approaches expiry.

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Why Choose Diligence Certification?

A PESO consultant should not merely fill out an online application.

For an MDI project, useful support starts much earlier.

At Diligence Certification, the practical approach should be to review the proposed installation first and then determine the appropriate compliance route.

That can involve:

• Applicability assessment
• Document review
• Technical-document coordination
• Drawing review
• Application preparation
• Regulatory submission
• Query management
• Inspection preparation
• Deficiency coordination
• Approval follow-up
• Renewal and modification guidance

This approach is particularly valuable when the MDI installation is part of a larger polyurethane plant.

For related technical compliance, businesses can also refer to Diligence Certification’s guides on PESO License for Pressure Vessels and Static Pressure Vessel License in India.

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Conclusion

PESO Approval for MDI Storage should begin with one question: What exactly is the regulatory status of this particular storage installation?

MDI is an important raw material for polyurethane manufacturing, but the presence of MDI alone does not provide enough information to determine the PESO route. The storage vessel, pressure conditions, design, installation, safety systems and applicable rules all need to be considered together.

For a new project, the best time to assess compliance is before the tank is fabricated and before the civil layout becomes fixed. For an existing facility, the first step should be a technical and regulatory gap assessment.

Diligence Certification can assist businesses in assessing the applicable PESO requirements, preparing documentation, coordinating technical compliance and supporting the approval process for regulated storage and pressure-vessel installations.

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Frequently Asked Questions