What Is Vendor Documentation? MDR and VDR

Quick Answer

Vendor documentation is the complete set of technical documents that a supplier must submit to the buyer as part of a purchase order. These documents prove that the supplied materials meet the specified requirements. The Master Document Register (MDR) lists all required documents; the Vendor Document Register (VDR) tracks their submission and approval status. In EPC projects, vendor documentation is contractually mandated and must be approved before materials are shipped.

MDR: Master Document Register

The MDR is created by the buyer’s engineering team and included in the MRQ/RFQ package. It specifies every document the vendor must provide, including the required format, number of copies, and submission deadline.

MDR Field	Description	Example
Document code	Standardized classification	A (for approval), B (for information), C (as-built)
Document title	Name of the required document	General arrangement drawing
Document type	Drawing, calculation, datasheet, report, certificate	Datasheet
Submission timing	When to submit relative to manufacturing	Before start of manufacturing
Review code	Required level of buyer review	A1 = Approval required before work starts

Standard Vendor Document Codes

Code	Meaning	Buyer Action	Vendor Can Proceed?
A1	Approval required before manufacturing	Must review and approve	No—wait for approval
A2	Approval required before shipment	Must review and approve	Can manufacture, cannot ship
B1	For information / record only	Review optional	Yes—no approval needed
B2	For information, comment if necessary	May comment	Yes—vendor notes comments
C	As-built / final documentation	File for project records	N/A (post-shipment)

Typical Vendor Documents for Piping Materials

Document	Applies To	Code (Typical)
Mill test certificates (MTC)	Pipes, fittings, flanges, plates	A2 or B1
Chemical analysis report	All metallic materials	A2
Mechanical test report	Tensile, impact, hardness	A2
Heat treatment records	Alloy and sour service materials	A2
NDE reports	Radiography, UT, MPI, PT	A2
Hydrostatic test report	Pipes, valves, pressure vessels	A2
Dimensional inspection report	Fittings, flanges, valves	A2 or B1
Coating/painting report	Coated pipes, painted valves	B1
Packing and marking procedure	All shipments	B1
Weld procedure specification (WPS)	Welded items	A1
Procedure qualification record (PQR)	Welded items	A1

VDR: Vendor Document Register

The VDR is the tracking tool that records the status of every document listed in the MDR. Both buyer and vendor maintain the VDR throughout the order lifecycle.

VDR Field	Content
PO number	Purchase order reference
Document title	Per MDR
Revision	Current document revision
Vendor submission date	Date vendor submitted the document
Buyer review status	Under review / Approved / Approved with comments / Rejected
Buyer response date	Date buyer returned comments
Resubmission date	If rejected, date of revised submission
Final status	Approved / Outstanding

Common Mistake

Delaying document review on the buyer side. The PO typically requires the buyer to review and return vendor documents within 10-14 working days. If the buyer takes 4-6 weeks to review, the vendor’s manufacturing schedule slips by the same amount. Late document reviews are one of the most common—and most preventable—causes of delivery delays in EPC projects.

Document Submission Process

Step	Activity	Timeline
1	Vendor submits documents per MDR schedule	Per PO milestones
2	Document control logs receipt and distributes for review	1-2 days
3	Engineering reviews against specification	10-14 working days
4	Comments returned to vendor (or approval issued)	Same day as review completion
5	Vendor resubmits revised documents (if required)	5-10 days
6	Final approval issued	5-7 days

Vendor documentation is not administrative overhead—it is the evidence that materials comply with project specifications. Incomplete or non-compliant documentation delays inspection release, shipment, and ultimately construction. For hydrostatic test documentation and shipping document requirements, see the detailed guides.

Read the full guide to pipe classes and specifications