NSF has tested and certified drinking water components for more than 70 years. The certification process is organized into seven clearly defined steps. The sequence is typically the same across component types, including valves, flanges, and other pipe fittings. But what happens in each step varies depending on the product being certified. This guide explains the full certification process for stainless steel flanges to NSF/ANSI/CAN 61.
The Seven Steps of NSF Certification
Step | Name | What Happens for a Flange |
1 | Application | The manufacturer applies, identifying the specific flange series, size range, and material grade |
2 | Submission | Alloy composition, manufacturing method, and any gasket or seal materials in the assembly are disclosed in full |
3 | Review | NSF’s technical team reviews the formulation and parts list line by line, confirming alloy grades and identifying what needs testing |
4 | On-Site Audit | An auditor visits the actual foundry, forge, or machine shop and collects or requests representative samples |
5 | Testing | Samples undergo laboratory extraction testing, simulating drinking-water contact under controlled conditions |
6 | Technical Evaluation | Review findings, audit results, and lab data are combined into a single pass/fail determination |
7 | Certification | The NSF mark is granted if the product passes and then maintained annually through continued audits, not a one-time approval |
NSF Certification for Flanges
Step 1: Application
The manufacturer submits a formal application identifying the specific product line. In this case, that means a flange series by type, size range, and material grade, not just a general product category.
Step 2: Submission
During this stage, the manufacturer hands over the technical details. NSF describes this step as providing product formulation, toxicology, and product use information. For a flange, that means alloy composition, casting or forging method, any coatings or surface treatments, and the intended end use. It also discloses any non-metallic components in the assembly, such as gaskets and seals, alongside the metal body. That matters because fluoropolymer gaskets and seals can trigger additional PFAS testing.
Step 3: Review
NSF’s technical team reviews the submitted formulation and parts list line by line. For a flange line, that means confirming the alloy grade matches what’s claimed, such as 304/304L or 316/316L stainless steel. It also means identifying which components need laboratory testing.
Step 4: On-Site Audit
An auditor visits the actual manufacturing facility, whether that is the foundry, forge, or machine shop. The auditor collects or requests samples directly from the line. This step confirms the parts being produced match what was disclosed in Step 2, not just what’s described in a catalog. A self-declared compliance claim skips this step entirely, which is why NSF treats certification and compliance as different things.
Step 5: Testing
Representative flange samples go to the lab for extraction testing. The test simulates contact with drinking water under controlled conditions. It measures what, if anything, leaches out against the standard’s contaminant thresholds.
Step 6: Technical Evaluation
NSF completes a final technical evaluation. It pulls the review, audit findings, and lab results into a single pass/fail determination against the full standard, not just the individual test results in isolation.
Step 7: Certification
Certification is granted, and the flange line can carry the NSF mark. But this step doesn’t close the file. Certification is maintained annually, so the facility remains subject to ongoing audits and surveillance rather than a one-time sign-off. We cover what that ongoing obligation involves in How NSF Certification Is Earned.
What Manufacturers Need to Prepare for NSF Certification
The process moves faster when the paperwork is already in order. For flanges specifically, that generally means:
- Alloy composition and grade documentation for every material in the line, matched against current Mill Test Reports
- A clear parts list broken out by size, class, and facing type, not a single blanket description covering an entire product family
- Documentation of the manufacturing method, forged, cast, or cut from plate, since this affects what the on-site audit verifies
- Any gasket, seal, or non-metallic component specs, submitted alongside the metal body rather than treated as a separate, unrelated item
What Affects the NSF Certification Timeline?
The certification timeline depends heavily on how complete the initial submission is and how much laboratory testing a given material or size range requires. What stays consistent is that the seven steps always happen in the same order. Incomplete or inconsistent documentation at the submission stage is the most common reason a certification timeline runs longer than expected.
Conclusion
The seven-step process is the same structure NSF applies across drinking water products, but for a flange it comes down to a specific set of deliverables. Those include accurate material documentation, a clean parts list, a facility that matches what’s on paper, and lab results that meet the standard’s thresholds.
Every flange in API International’s CleanLine follows these steps. Explore our online product catalog for a comprehensive range of flanges, or contact us for custom machining in nonstandard sizes and configurations. Get connected with a dedicated sales representative today, or call us at 503.692.3800.
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