How to Specify Non-Destructive Testing (END) in Purchase Proposals (RFQ)

A practical guide for purchasers and supply engineers.

In industry, Non-Destructive Testing (END) is fundamental to ensuring the quality, safety, and conformity of parts and equipment. However, many Requests for Quotations (RFQs) fail because they do not correctly specify what is being requested—whether it is the contracting of END services or the acquisition of supplies and equipment to perform it.

Below, we present a practical guide to preparing clear and complete RFQs, with real-world examples from Metal-Chek and Supermagna products .

1. Define what you are buying: a service or a supply.

First of all, determine if your RFQ will be for:

END service – the supplier performs the test and delivers the technical report.
Materials/supplies/equipment for END – your team or service provider will use the purchased products to perform the test.

This distinction avoids confusion and ensures that the specifications are suitable for what you want to buy.

2. Specifying the contracting of the END service

When hiring a service, describe how the test should be conducted and what acceptance criteria will be adopted.

a) Method and technique

Specify the method and technique:

Example: Liquid penetrant testing, Type I, Method A, Level 2, using Metal-Chek FP 91
Example: Dry magnetic particle extraction, white powder, using Supermagna WD 55

b) Reference standard

Define the applicable standard (ASTM E165, ASTM E709, ASME Section V, AWS D1.1 or internal standards such as Petrobras N-1596/N-1598).

c) Acceptance criteria

Determine codes and levels (e.g., ASME VIII Div.1, EN 1369, Level 2 or 3).

d) Inspector qualifications

Require SNQC/ABENDI or ASNT SNT-TC-1A certification , Level II or III, depending on the method.

e) Implementation conditions

Include requirements such as cleanliness, adequate lighting (lux or µW/cm²), temperature, humidity, and application times.

f) Documentation and traceability

Request reports with photos, sketches, and part identification, ensuring traceability by batch or serial number.

3. Specifying the purchase of materials and equipment for END

When purchasing supplies or equipment, the RFQ (Request for Quotation) should contain technical details of the product .

a) Penetrant Liquids

Fluorescent: Metal-Chek FP 91 , Type I, Method A, Level 2
Visible: Metal-Chek VP 30 , Type II, Method A
Visible: Metal-Chek VP 31 , Type II, Method C

b) Developers

Dry: Metal-Chek D72 , form a
Non-aqueous: Metal-Chek D70 , form d, e
Aqueous: Metal-Chek D76 , form b

c) Removers / Cleaners

Solvent: Metal-Chek E 59 , Class 2
Solvent: Metal-Chek R 501 , Class 1

d) Magnetic Particles

White dry track: Supermagna WD 55
Yellow dry track: Supermagna YD 404
Fluorescent wet process: Supermagna LY 2000
Visible red wet path: Supermagna RW 222
Visible black wet sample: Supermagna BW 333

e) Equipment

Yokes: Supermagna Yoke HMM6

4. Best practices for any END RFQ

Be specific: avoid generic terms like “LP test” without specifying the method, type, and standard.
Standardize the descriptions across all requests.
Approve the technical proposal before the price.
Include safety and environmental requirements (PPE, proper disposal of products).

Conclusion

A clear specification — whether for contracting END services or acquiring Metal-Chek and Supermagna supplies — ensures that the process is executed with quality, reduces risks, and avoids rework.

Want to learn more? Read also: How to choose the ideal penetrant type for each application .

Speak to our technical team .