Blower GA Drawing Approval, MTC and PMI Documentation: Buyer Checklist Before Manufacturing
Blower GA drawing approval is the point where the buyer, consultant and manufacturer freeze the blower layout before manufacturing starts. MTC confirms the material certificate and heat/batch traceability. PMI confirms whether selected metallic parts match the specified grade. For industrial centrifugal blowers used in chemical plants, pharma plants, boiler systems, scrubbers, bag filters, cement plants and high-temperature applications, these documents reduce wrong fabrication, wrong material selection, dispatch delays and site installation disputes.
At AS Engineers, we treat documentation as part of the blower supply scope, not as an afterthought. When documentation requirements are clear at the enquiry stage, the GA drawing, QAP, MTC, PMI, inspection reports and test certificates can be planned properly before production.
Why documentation matters before blower manufacturing
Many blower problems do not begin after installation. They begin before manufacturing, when the drawing, material grade, orientation, inspection scope or documentation requirement is not clearly agreed.
A centrifugal blower may look simple from outside, but the final supply can include impeller, casing, shaft, bearing housing, base frame, motor, coupling or pulley drive, guards, damper, expansion bellow, inspection door, drain, lifting lugs, foundation holes, paint system and site-specific accessories.
If these details are not frozen before fabrication, the buyer may face:
| Documentation gap | Practical site problem |
|---|---|
| GA drawing not approved properly | Wrong discharge orientation, foundation mismatch or duct alignment issue |
| MOC not clearly marked | Wrong material selected for corrosive, abrasive or high-temperature duty |
| MTC not asked in PO | Material traceability becomes difficult during QA review |
| PMI not defined in QAP | Alloy verification may be missed for SS or special material components |
| Accessories not shown in drawing | Damper, bellow, guard or inspection door may not match site expectation |
| Inspection stages not agreed | Buyer or TPI may ask for hold points after fabrication has already moved ahead |
| Test certificate format not finalized | Dispatch may be delayed during documentation review |
For a broader selection base, read AS Engineers’ guide on industrial blowers manufacturer in India and centrifugal fans.
What is blower GA drawing approval?
GA means General Arrangement. A blower GA drawing is the approved layout drawing that shows how the blower will be manufactured, assembled, connected, mounted and installed at site.
For a centrifugal blower, GA drawing approval normally covers:
- Overall dimensions
- Inlet and outlet size
- Discharge orientation
- Rotation direction
- Shaft and drive arrangement
- Motor position
- Base frame dimensions
- Foundation hole details
- Centre height
- Inlet and outlet flange details
- Damper, bellow, guard and other accessories
- Inspection door and drain position
- Approximate equipment weight
- Maintenance access direction
- Lifting arrangement where applicable
- Paint or finish note when included in scope
A GA drawing is not only a layout sketch. It becomes the manufacturing reference for fitment, site coordination, duct routing, foundation planning and buyer approval.
GA drawing approval is not the same as performance approval
This is one of the most common buyer-side mistakes.
GA approval confirms the physical arrangement and agreed construction details. It does not automatically confirm that the blower will meet airflow, static pressure, temperature, dust load, noise, vibration or power requirements unless those performance values are also listed and accepted in the approved technical documents.
For performance-related approval, the buyer should also check:
| Item | What to verify |
|---|---|
| Airflow | CFM or CMH at actual duty condition |
| Static pressure | mmWC, mmWG or Pa, clearly stated |
| Gas temperature | Normal and maximum inlet temperature |
| Gas condition | Dust, fumes, moisture, corrosive components |
| Density and altitude | Required for correct fan selection where applicable |
| Motor rating | HP/kW, voltage, frequency, enclosure and efficiency class |
| RPM | Blower RPM and motor RPM |
| Fan curve | Required where project specification asks for it |
| Test method | IS, AMCA, ISO or project-specific method, if applicable |
| Tolerance | Accepted performance tolerance as per PO or agreed standard |
If the blower is for a boiler, furnace, scrubber, bag filter or process exhaust duty, the GA drawing should be reviewed together with the datasheet and performance requirement. You can also refer to AS Engineers’ resources on boiler fan and ID fan manufacturers and centrifugal blowers for dust collection systems.
What buyers should check before approving a blower GA drawing
Before approving the GA drawing, check these points carefully.
| GA drawing point | Buyer check |
|---|---|
| Equipment tag number | Match with PO, datasheet and project list |
| Blower model or type | Confirm backward curved, backward inclined, radial blade or special design |
| Rotation direction | Confirm clockwise or counter-clockwise from drive end or as defined in drawing |
| Discharge orientation | Match site duct layout |
| Inlet orientation | Confirm duct approach, filter, silencer or inlet box requirement |
| Foundation holes | Match civil foundation plan |
| Centre height | Confirm with duct and motor alignment requirement |
| Flange drilling | Match ducting, damper or expansion bellow connection |
| Base frame | Confirm common base frame, motor slide rail or separate base scope |
| Drive arrangement | Direct drive, belt drive, coupling drive or project-specific arrangement |
| Guarding | Coupling guard, belt guard and rotating part protection |
| Maintenance access | Bearing, inspection door and impeller access should be practical |
| Accessories | Damper, bellow, drain, inspection door, cooling disc, seal or stuffing box |
| Weight | Useful for unloading, foundation and lifting planning |
| Paint shade | Confirm only when paint system or shade is part of scope |
| Documentation notes | QAP, MTC, PMI, NDT, balancing and test reports if required |
Do not approve the drawing only because the main dimensions look correct. For a blower, small orientation or connection errors can create large installation delays.
What is MTC in blower documentation?
MTC means Material Test Certificate. In blower documentation, MTC is used to verify that the supplied raw material or bought-out metallic part matches the specified material grade.
For blower fabrication, MTC may be required for:
- Casing plate
- Impeller plate
- Shaft
- Hub
- Base frame material
- Stainless steel or alloy steel contact parts
- High-temperature components
- Critical fasteners, if specified
- Bought-out items, if included in the project documentation scope
A useful MTC should show:
| MTC field | Why it matters |
|---|---|
| Material grade | Confirms the material specification |
| Heat number / batch number | Enables traceability |
| Chemical composition | Confirms element percentage against grade |
| Mechanical properties | Confirms strength-related values where applicable |
| Thickness or size | Helps match material with component requirement |
| Certificate number | Supports documentation tracking |
| Supplier / mill reference | Supports source traceability |
| Standard reference | Confirms applicable material standard when stated |
| Authorized signatory | Confirms certificate validity |
MTC is especially important for SS, alloy steel, high-temperature, corrosive gas, pharma, chemical and EPC project requirements.
What is PMI in blower documentation?
PMI means Positive Material Identification. PMI is a verification test used to check the material grade of selected metallic components without destroying the part.
In simple terms:
- MTC is document-based material traceability.
- PMI is physical material verification on the component or raw material.
PMI is commonly asked for stainless steel, alloy steel and special material parts where material mix-up can create corrosion, temperature or process compatibility risks.
For blowers, PMI may be applied to:
| Component | PMI relevance |
|---|---|
| SS casing parts | Confirms stainless steel grade where gas contact is critical |
| SS impeller | Important for corrosive or clean-process duty |
| Alloy shaft or special shaft material | Useful for high load or project-specified material |
| High-temperature parts | Helps verify material identity before dispatch |
| Welded contact parts | Useful when process gas compatibility is important |
| Special fasteners | Required only when project specification demands it |
PMI scope should not be assumed. It should be written clearly in the PO, QAP or inspection plan.
MTC vs PMI: what is the difference?
| Point | MTC | PMI |
|---|---|---|
| Full form | Material Test Certificate | Positive Material Identification |
| Type | Document | Physical verification |
| Purpose | Confirms material certificate and test values | Confirms actual material identity on selected item |
| Based on | Mill / supplier certificate | On-site or shop-floor test instrument |
| Common use | Material traceability | Alloy grade verification |
| Required for all blowers? | Not always. Depends on PO and project specification | Not always. Usually for SS, alloy or critical duty |
| Best stage | Before fabrication and during document review | Before or during fabrication, before dispatch |
| Buyer risk reduced | Wrong certificate or missing traceability | Material mix-up or wrong grade used |
For critical applications, use both. MTC alone does not physically prove that the exact component installed in the blower is the same material unless traceability is maintained properly.
What is QAP for blower manufacturing?
QAP means Quality Assurance Plan. It defines what will be checked, when it will be checked, who will witness it, and which document will be generated.
For centrifugal blowers, a QAP may include:
- Raw material inspection
- MTC review
- PMI, if applicable
- Dimensional inspection
- Welding inspection
- NDT, if applicable
- Shaft inspection
- Impeller inspection
- Dynamic balancing
- Assembly inspection
- Alignment check
- Mechanical run test
- Vibration check
- Noise check, if specified
- Performance test, if specified
- Paint inspection
- Final inspection
- Packing and dispatch inspection
A good QAP avoids confusion between buyer, manufacturer and third-party inspection agency.
Typical blower documentation list for industrial projects
The final document requirement depends on project specification, industry, application and PO scope. For industrial centrifugal blowers, buyers commonly ask for:
| Document | Purpose |
|---|---|
| Approved GA drawing | Layout and manufacturing approval |
| Technical datasheet | Duty condition and performance reference |
| QAP / ITP | Inspection and quality stage plan |
| MTC | Material test certificate |
| PMI report | Material identity verification where applicable |
| NDT report | Weld or component inspection where applicable |
| Dynamic balancing report | Impeller balancing confirmation |
| Mechanical run test report | Running, vibration and noise observation |
| Performance test report | Airflow, pressure and power confirmation when specified |
| Motor test certificate | Bought-out motor documentation |
| Bearing certificate | Bought-out bearing documentation when required |
| Paint inspection report | DFT or paint system check when specified |
| Calibration certificates | For measuring instruments used during testing |
| Packing list | Dispatch verification |
| Warranty document | Commercial documentation as per offer |
| O&M manual | Installation, operation and maintenance guidance |
When documentation is required for pharma, chemical, EPC or government projects, specify it at the enquiry stage. Adding documentation scope after manufacturing starts can delay approval and dispatch.
When should PMI be mandatory?
PMI should be considered when the blower handles corrosive, high-temperature, reactive, critical or clean-process gas, or when project specifications demand material verification.
PMI is more relevant for:
- SS 304 / SS 316 / SS 316L construction
- Alloy steel components
- Pharma and GMP-linked areas
- Chemical fumes and corrosive gas handling
- High-temperature process air
- Petrochemical or refinery-related projects
- EPC projects with third-party inspection
- Export or documentation-heavy project supplies
- Replacement blowers where original MOC must be matched
PMI may not be necessary for every standard MS blower. For a normal ventilation or general air blower, the buyer may only need GA drawing, datasheet, balancing report and test certificate. The correct scope depends on duty criticality.
Common mistakes buyers make during blower approval
Approving GA drawing without checking rotation
Rotation error can affect duct connection, drive arrangement and impeller operation. Always confirm rotation direction as defined in the drawing.
Not checking discharge orientation
Discharge orientation must match actual duct layout. A small orientation mismatch can force site modification.
Asking for MTC after fabrication is complete
MTC should be requested at the PO or QAP stage. Late requests create traceability and documentation delays.
Assuming PMI is included by default
PMI is not always included unless specified. It should be written in the enquiry, PO, QAP or inspection requirement.
Not defining inspection hold points
If TPI or consultant approval is required, hold points should be agreed before manufacturing.
Checking only motor HP
Motor HP alone does not confirm blower suitability. Airflow, static pressure, temperature, gas condition, density, duty cycle and system resistance matter.
Ignoring accessory documentation
Damper, bellow, mechanical seal, stuffing box, guards and bearing assemblies should be included in the drawing or document list when they are part of the scope.
Buyer-side checklist before releasing manufacturing clearance
Use this checklist before sending “Approved for Manufacturing” on a blower GA drawing.
| Checklist item | Status |
|---|---|
| GA drawing revision number checked | |
| Tag number and project name matched | |
| Airflow and static pressure matched with datasheet | |
| Inlet temperature and gas condition reviewed | |
| MOC checked for casing, impeller and shaft | |
| Rotation and discharge orientation approved | |
| Foundation hole details checked | |
| Flange drilling and duct connection checked | |
| Motor rating and drive arrangement reviewed | |
| Guards and safety covers included where required | |
| Damper, bellow, seal, drain and inspection door checked | |
| QAP / ITP approved | |
| MTC requirement finalized | |
| PMI requirement finalized | |
| NDT requirement finalized, if applicable | |
| Dynamic balancing requirement finalized | |
| Mechanical run test requirement finalized | |
| Performance test requirement finalized | |
| Paint shade and DFT requirement finalized, if applicable | |
| Final document dossier list agreed |
What AS Engineers reviews before blower documentation is finalized
For industrial centrifugal blower enquiries, AS Engineers reviews process and site data before finalizing the blower configuration. Important inputs include airflow, static pressure, temperature, dust load, humidity, density, altitude, MOC, impeller blade design, motor mounting arrangement and required quality documentation.
AS Engineers’ centrifugal blower range includes backward curved blowers, backward inclined blowers, high-pressure radial blade blowers, exhauster radial blowers, high-temperature plug blowers and exhauster air handling blowers. Selection depends on the actual application, not only the blower name.
Typical industries include steel and metals, automobile, power plants, fertilizer and chemical, refinery and petrochemical, cement and food processing. For application-specific context, see AS Engineers’ pages on centrifugal blowers for steel and metal industries, centrifugal blowers for cement industry and fans for fertilizer and chemical industry.
Recommended RFQ inputs for blower documentation
When sending a blower enquiry, include these inputs:
- Application name
- Process industry
- Airflow required in CFM or CMH
- Static pressure in mmWC, mmWG or Pa
- Inlet gas temperature
- Gas composition
- Dust load
- Moisture or humidity
- Corrosive components, if any
- Site altitude and ambient condition, if critical
- Required MOC
- Preferred impeller type, if known
- Drive arrangement preference
- Motor specification
- Inlet and outlet orientation preference
- Space restriction
- Foundation details, if existing
- Required accessories
- GA drawing approval requirement
- MTC requirement
- PMI requirement
- NDT requirement
- Third-party inspection requirement
- Performance test requirement
- Dispatch documentation format
A clear RFQ helps the manufacturer quote correctly and prevents avoidable revision cycles later.
Fit and no-fit guidance
| Requirement | Documentation recommendation |
|---|---|
| Standard MS blower for general air | GA drawing, datasheet, balancing report, test certificate |
| Boiler FD/ID fan | GA drawing, datasheet, balancing, mechanical run, performance test if specified |
| Scrubber ID fan | Add MOC confirmation, corrosion review, MTC where required |
| Bag filter fan | Add dust load, abrasion review and impeller/balancing focus |
| Chemical process blower | Add MTC, PMI, NDT and QAP where project demands |
| Pharma SS blower | Add SS MTC, PMI, surface finish and weld inspection records where required |
| High-temperature blower | Add material review, temperature-rated construction and special inspection plan |
| EPC / consultant-led project | Add QAP, ITP, TPI hold points and final documentation dossier |
Conclusion
Blower GA drawing approval, MTC and PMI documentation should be finalized before manufacturing starts. GA approval prevents layout, foundation and ducting mistakes. MTC supports material traceability. PMI verifies actual material identity for critical metallic components. QAP ties the full inspection process together.
For a standard blower, a simple documentation package may be enough. For pharma, chemical, EPC, high-temperature, corrosive or critical process duty, the documentation scope should be clearly written in the enquiry and PO. This avoids late-stage disputes and helps the manufacturer plan material procurement, inspection, testing and dispatch without unnecessary delay.
If you are planning a centrifugal blower for a boiler, scrubber, bag filter, chemical plant, dust collection system, furnace, dryer or process exhaust application, share your duty data and documentation requirements with AS Engineers at the enquiry stage. The team can review GA drawing, MOC, accessories, QAP, MTC, PMI and testing scope based on actual site conditions.
FAQs
What is blower GA drawing approval?
Blower GA drawing approval is the buyer’s confirmation of the blower’s general arrangement, including dimensions, rotation, inlet-outlet orientation, foundation details, drive arrangement, accessories and connection points. Manufacturing should begin only after the approved drawing revision is clear.
Is MTC required for every centrifugal blower?
Not always. MTC is usually required when the buyer, consultant, EPC, pharma plant, chemical plant or project specification asks for material traceability. It is more important for SS, alloy, high-temperature, corrosive and critical duty blowers.
What is PMI in blower manufacturing?
PMI, or Positive Material Identification, is a physical material verification test used to confirm that selected blower components match the specified metal grade. It is commonly used for stainless steel, alloy steel and critical process applications.
What is the difference between MTC and PMI?
MTC is a material certificate from the mill or supplier. PMI is a physical verification test on the material or component. MTC supports traceability, while PMI helps confirm that the actual part matches the required material grade.
When should QAP be approved for a blower?
QAP should be approved before fabrication starts. It defines inspection stages, witness points, hold points, document review points and final test requirements. Late QAP approval can delay manufacturing and dispatch.
