1. Why These Mistakes Are So Common
EP pipes look simple to buy: pick a size, ask for "EP finish", compare prices. But the product has several variables that a bright surface hides: grade, wall, Ra, where EP is applied, documents, packing and handling.
Most problems come not from bad suppliers but from incomplete specifications. When the order is vague, the supplier fills the gaps with whatever is cheapest or easiest. The mistakes below are the ones that show up most often, with a fix for each.
2. Mistakes 1-2: Specification Gaps
Mistake 1: Ordering "EP pipe" without a Ra value.
Without a number, there is nothing to measure or reject.
Fix: State a maximum Ra with unit, the surface (inside, outside or both) and the measurement method, for example "Ra ≤ 0.5 µm (20 µin), inside, per lot".
Mistake 2: Assuming EP is applied inside and outside.
Many quotes cover outside-only EP unless stated. For process lines, the inside is what matters.
Fix: Write the EP location clearly on the enquiry and the purchase order, and confirm it in the quotation.
3. Mistakes 3-4: Wrong Grade and Wrong Comparison
Mistake 3: Choosing the grade by habit.
Using 304 because "we always did" can fail in chloride-rich or acidic service, while using 316L everywhere can waste money on utility lines.
Fix: Match the grade to the media, cleaning chemicals, location and risk. Confirm composition on the MTC.
Mistake 4: Comparing quotes on price alone.
The cheapest quote often leaves out the finish, the documents, the inspection or the packing.
Fix: Use a comparison sheet with identical grade, size, tolerance, Ra, EP location, documents, packing and delivery terms.
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4. Mistakes 5-6: Paperwork and Traceability
Mistake 5: Accepting pipes without an MTC, or with a generic certificate.
A certificate not linked to the heat number on the pipe is worthless in an audit.
Fix: Require MTCs per EN 10204 3.1 (or as agreed), with heat numbers marked on the pipes, and check them against the delivery.
Mistake 6: No Ra report or passivation record.
Buyers often realise this at validation, when it's too late to produce the data.
Fix: Include the Ra report and passivation or cleanliness certificate in the purchase order as deliverables, tied to the lot.
5. Mistakes 7-8: Handling and Contamination
Mistake 7: Poor packing and rough handling.
Pipes dragged across carbon steel racks or shipped without end caps pick up scratches and iron contamination, which can cause rust spots on a brand-new EP surface.
Fix: Specify end-capped, clean-wrapped packing with protection from carbon steel contact, and instruct your site team on handling.
Mistake 8: Using carbon steel tools and storage on site.
Wire brushes, grinding discs and racks previously used on carbon steel leave embedded iron on stainless.
Fix: Use dedicated stainless tools and storage, and keep fabrication areas for stainless separate from carbon steel work.
6. Mistakes 9-10: Welding and Inspection
Mistake 9: Ignoring weld quality and skipping passivation after fabrication.
Heat tint at welds, poor purge gas and rough internal beads undo the benefit of a smooth pipe.
Fix: Use orbital welding with proper purge control where required, inspect welds (borescope for critical lines) and carry out passivation after welding as per your specification.
Mistake 10: Not inspecting on receipt, and buying in bulk without a sample.
Problems found after installation are expensive to fix.
Fix: Check a sample first, then inspect each delivery for visual finish, dimensions, markings, packing and documents before accepting. Where it matters, measure Ra on a sample or use third-party inspection.
7. A Pre-Order Checklist You Can Reuse
Before you send the purchase order, confirm that you have stated:
- Grade and standard (for example 316L, ASTM A270)
- OD, wall thickness, length and tolerance
- Seamless or welded
- EP surface (inside, outside or both) and maximum Ra with unit
- Documents required (MTC type, Ra report, passivation certificate, PMI)
- Inspection requirement (own, third-party, witnessed)
- Packing and marking requirements
- Delivery terms, quote validity and acceptance criteria
If any line is blank, the supplier will decide for you.