A well-prepared RFQ is the foundation of a successful Pressure Vessel Fabrication project. It gives manufacturers the technical information needed to calculate an accurate price, schedule, materials, inspection, and documentation. IESCON understands that a clear RFQ reduces misunderstandings, uncontrolled changes, and unexpected costs throughout pressure vessel fabrication and delivery.
What Is an RFQ for Pressure Vessel Fabrication?
An RFQ, or Request for Quotation, is a formal document sent to qualified fabrication companies to request a technical and commercial offer for manufacturing a pressure vessel.
A good RFQ should tell the fabricator exactly what the buyer needs without leaving critical technical requirements open to interpretation.
For Pressure Vessel Fabrication, the RFQ normally defines:
- Vessel type and service
- Design pressure and temperature
- Operating pressure and temperature
- Dimensions and capacity
- Materials
- Applicable codes and standards
- Welding requirements
- Inspection and testing
- Corrosion allowance
- Nozzles and connections
- Internal and external components
- Surface treatment
- Documentation
- Delivery requirements
- Installation requirements
- Commercial terms
ASME Section VIII, Division 1 addresses pressure vessel design and construction requirements, including materials, fabrication, inspection, testing, and certification.
What Information Should an RFQ for Pressure Vessel Fabrication Include?
The RFQ should provide enough information for every bidder to quote the same scope.
A practical RFQ structure can include the following:
| RFQ Section | Information to Include |
| Project information | Project name, location, client, required delivery date |
| Vessel data | Type, service, capacity, orientation |
| Design conditions | Pressure and temperature |
| Materials | Shell, heads, nozzles, supports |
| Codes | ASME and applicable standards |
| Welding | WPS, PQR, welder qualification requirements |
| Inspection | VT, RT, UT, PT, MT and other required examinations |
| Testing | Hydrostatic or other specified testing |
| Coating | Surface preparation and coating system |
| Documentation | Drawings, certificates, reports and data books |
| Delivery | Packing, transportation and delivery location |
| Commercial | Price basis, payment terms, validity and exclusions |
The more complete the RFQ, the easier it becomes to compare quotations on an equal technical basis.
Pressure Vessel Design and Technical Specifications
Design information is one of the most important parts of an RFQ.
The buyer should clearly identify whether the vessel is intended for gas, liquid, steam, chemical service, hydrocarbon service, or another process application.
The RFQ should also identify:
- Vessel orientation: horizontal or vertical
- Internal volume
- Design pressure
- Design temperature
- Operating pressure
- Operating temperature
- Vacuum or external pressure requirements
- Corrosion allowance
- Design life
- Process fluid
- Specific gravity where applicable
- Required nozzle connections
- Support type
- Insulation requirements
- Internal components
If the vessel will experience cyclic loading, thermal cycling, vacuum conditions, or unusual external loads, these conditions should be stated before fabrication pricing begins.
This information allows the fabricator to understand the actual design basis instead of making assumptions.
Materials and Fabrication Requirements
Material requirements should be stated clearly in the RFQ.
Depending on the design and service, the specification may define materials for:
- Shell plates
- Heads
- Nozzles
- Flanges
- Pipes
- Supports
- Reinforcement pads
- Internal components
- Welding consumables
Material traceability is particularly important for pressure equipment. ASME’s Section VIII learning material specifically addresses allowable materials and material traceability as part of pressure vessel construction.
The RFQ should therefore specify whether the manufacturer must provide:
- Material test certificates
- Heat numbers
- Material traceability records
- Approved material grades
- PMI requirements
- Replacement material approval procedures
A strong RFQ should also define fabrication requirements such as cutting, forming, rolling, machining, fit-up, welding, dimensional tolerances, and heat treatment where applicable.
Applicable Codes and Standards
An RFQ must clearly identify the governing code.
For many industrial pressure vessels, ASME BPVC Section VIII is a key reference. Division 1 contains requirements for the design, fabrication, inspection, testing, and certification of pressure vessels.
Depending on the project, the RFQ may also reference standards for:
- Welding qualifications
- Non-destructive examination
- Flanges and piping connections
- Materials
- Pressure relief devices
- Painting and coating
- Dimensional tolerances
- Inspection
- Transportation
The RFQ should identify the required edition of each code or standard where the project specification requires a specific edition.
Do not simply write “ASME compliant” without defining the applicable section, division, edition, and project-specific requirements.
Welding, Inspection, and Testing Requirements
Welding is a critical part of Pressure Vessel Fabrication because weld quality directly affects pressure integrity.
The RFQ should define the expected welding and inspection requirements, including:
- Welding procedures
- Welder qualifications
- Welding consumables
- Preheating requirements
- Post-weld heat treatment when applicable
- Weld identification
- Visual inspection
- Radiographic testing
- Ultrasonic testing
- Magnetic particle testing
- Liquid penetrant testing
- Hydrostatic testing
- Pneumatic testing when specifically justified and permitted
- Final inspection
ASME’s Section VIII material specifically covers welding, fabrication, NDE, testing, pressure relief, and documentation requirements.
Example
Suppose an RFQ requires a welded pressure vessel but only states “NDT as required.”
That wording leaves room for different interpretations.
A stronger RFQ would specify the required examination method, examination percentage or extent where applicable, acceptance criteria, responsible inspection party, and documentation.
This makes quotations easier to compare and reduces disputes after the purchase order is issued.
Pressure Vessel Dimensions, Capacity, and Operating Conditions
Dimensions should be as specific as possible.
The RFQ should define:
- Overall dimensions
- Internal diameter
- Tangent-to-tangent length where applicable
- Vessel volume
- Shell thickness requirements if already engineered
- Head type
- Head dimensions
- Nozzle sizes and locations
- Support dimensions
- Lifting lugs
- Manways
- Platforms and ladders where required
Operating conditions should include both normal and design conditions.
| Parameter | Example RFQ Information |
| Service | Process gas |
| Orientation | Horizontal |
| Operating pressure | Project-specific |
| Design pressure | Project-specific |
| Operating temperature | Project-specific |
| Design temperature | Project-specific |
| Capacity | Project-specific |
| Corrosion allowance | Project-specific |
| Material | Code-approved grade |
| Testing | According to applicable code |
The values above are examples of RFQ fields, not universal design values. Actual values must come from the process design and engineering requirements.
Required Documentation and Quality Certificates
Documentation should be included in the RFQ from the beginning.
Waiting until the vessel is finished to request documents can create delays and incomplete records.
A typical documentation package may include:
- Approved drawings
- Design calculations
- Material certificates
- Welding procedures
- Welder qualifications
- Welding maps
- NDT reports
- Heat treatment records
- Dimensional inspection reports
- Pressure test records
- Coating reports
- Calibration certificates
- Inspection reports
- Non-conformance reports and corrective actions
- Final data book
- Manufacturer’s documentation required by the applicable code
ASME’s guidance on Section VIII specifically includes design reports, data reports, inspection, testing, certification, and documentation within the broader pressure vessel construction process.
Delivery, Installation, and Project Requirements
The RFQ should clearly define what happens after fabrication.
Specify whether the manufacturer is responsible for:
- Fabrication only
- Fabrication and testing
- Fabrication, coating, and delivery
- Fabrication and site installation
- Complete supply and installation
Other requirements may include:
- Delivery location
- Required delivery date
- Transportation method
- Loading and unloading
- Preservation
- Packaging
- Lifting arrangements
- Site access
- Installation supervision
- Commissioning support
- Warranty requirements
This distinction is important because two quotations can have similar prices while covering completely different scopes.
How to Compare Pressure Vessel Fabrication Quotes
Do not compare quotations based only on the final price.
Create a technical and commercial comparison matrix.
| Factor | Quote A | Quote B | Quote C |
| Base fabrication price | ✓ | ✓ | ✓ |
| Materials included | ✓ | ✓ | ✓ |
| NDT included | ✓ | ✓ | ✓ |
| Testing included | ✓ | ✓ | ✓ |
| Coating included | ✓ | ✓ | ✓ |
| Documentation included | ✓ | ✓ | ✓ |
| Delivery included | ✓ | ✓ | ✓ |
| Installation included | ✓ | ✓ | ✓ |
| Lead time | ✓ | ✓ | ✓ |
| Exclusions | Review | Review | Review |
A Better Comparison Process
Step 1: Confirm that all bidders received the same technical specification.
Step 2: Check whether the quoted vessel complies with the required code.
Step 3: Compare material grades and specifications.
Step 4: Compare welding and inspection requirements.
Step 5: Review testing and certification.
Step 6: Compare delivery dates.
Step 7: Review exclusions and assumptions.
Step 8: Compare the total project cost.
Step 9: Evaluate technical experience and quality systems.
Step 10: Select the best-value proposal, not necessarily the cheapest proposal.
Common Mistakes to Avoid When Preparing an RFQ
Poorly prepared RFQs can create significant commercial and technical problems.
1. Providing incomplete operating conditions
Pressure and temperature are fundamental design inputs and should not be omitted.
2. Not identifying the applicable code
A fabricator cannot reliably price compliance if the governing code is unclear.
3. Leaving inspection requirements vague
“Inspection as required” can lead to different interpretations between bidders.
4. Not specifying documentation
Quality documents should be defined before fabrication begins.
5. Ignoring transportation
Large vessels can require special transportation planning.
6. Comparing different scopes
One bidder may include coating and delivery while another excludes them.
7. Selecting based only on price
The lowest quotation may not represent the lowest total project cost.
8. Changing requirements after fabrication starts
Late technical changes can affect material procurement, engineering, schedule, and cost.
Questions to Ask a Pressure Vessel Fabrication Company
Before awarding the order, ask the fabrication company:
- What pressure vessel codes do you work to?
- What similar vessels have you fabricated?
- Can you provide relevant technical references?
- What materials can you fabricate?
- How do you control material traceability?
- Which welding procedures are available?
- How are welders qualified?
- What NDT capabilities are included?
- Which pressure tests are included?
- What quality documentation will be delivered?
- What is your estimated fabrication lead time?
- What are your quotation exclusions?
- What assumptions were used in your price?
- Can you support transportation or installation?
The answers should be documented rather than relying only on verbal commitments.
Frequently Asked Questions About Pressure Vessel Fabrication RFQs
1. What should be included in a pressure vessel RFQ?
A pressure vessel RFQ should include the vessel service, dimensions, capacity, design and operating conditions, materials, applicable codes, welding, inspection, testing, documentation, delivery requirements, and commercial terms.
2. Which code is commonly used for pressure vessel fabrication?
ASME BPVC Section VIII is a major code family for pressure vessel construction. Section VIII, Division 1 covers requirements related to design, materials, fabrication, inspection, testing, and certification.
3. Why are material certificates important?
Material certificates provide documented information about the supplied material and support material traceability. This is especially important for pressure-retaining components and code-controlled fabrication.
4. Should NDT requirements be included in the RFQ?
Yes. The RFQ should identify applicable NDT methods and the required extent or acceptance requirements where defined by the governing code and project specification. This allows bidders to price the same inspection scope.
5. How can I compare pressure vessel fabrication companies?
Compare technical compliance first, followed by materials, welding, inspection, testing, documentation, lead time, scope, exclusions, HSE, experience, and total cost. The lowest price should not automatically determine the award.
Conclusion: Preparing an Effective RFQ for Pressure Vessel Fabrication
A clear RFQ makes Pressure Vessel Fabrication easier to price, execute, inspect, and control. IESCON recognizes the importance of defining design conditions, materials, codes, welding, testing, documentation, delivery, and commercial scope before fabrication begins. A detailed RFQ reduces uncertainty and gives the project team a stronger basis for selecting the right fabrication solution.
Get a Clear Pressure Vessel Fabrication Quote
Planning a new pressure vessel for an industrial or engineering project?
Send your technical requirements to IESCON and discuss your Pressure Vessel Fabrication scope with an experienced project team. Get a clear technical approach, defined fabrication requirements, and a quotation based on your actual project needs.
Contact IESCON today and start your pressure vessel project with a well-defined RFQ.
