PPR Supplier Checklist: The RFQ Fields That Make Quotes Comparable

Three PP-R quotes land in your inbox on the same Tuesday. You sent all three suppliers the same enquiry. The unit prices are a third apart, every supplier insists the offer is complete, and none of them is lying. Before you conclude that the cheap one is cutting corners or that the expensive one is padding, check what you actually asked for.

A request that says “20 mm PP-R pipe, please quote” has not specified a product. It has specified a diameter, and left the supplier to choose the wall thickness, the pressure class, the fitting standard and the packing basis on your behalf. Each of them chose differently, legitimately, and now nothing on those three sheets is comparable.

This is a working checklist for the person who has to issue the request and defend the award. It is organised the way a request for quotation is actually built — line item first, then answers, then documents, then commercial terms — and every item carries the part nobody publishes: what a substantive supplier reply contains, and what an evasive one sounds like when it is dressed in good English. At the end, Hitze answers the same checklist about itself, including the three fields where the honest answer is “not published”.

Why three PPR quotes never match: the four fields nobody fixed

The gap between your three quotes is usually not dishonesty. It is the predictable result of four unstated variables, each of which a supplier must resolve to produce a number at all.

The largest is the pipe series. PP-R is classified dimensionally by series S, which relates to the standard dimension ratio as S = (SDR − 1) / 2. The series decides the wall thickness, and the wall thickness is the material — which is most of the cost. In EN ISO 15874-2:2013 dimension class A, a 20 mm pipe carries a minimum wall of 1,9 mm in series S5 and 3,4 mm in series S2,5. Both are 20 mm pipe. Both are compliant. The S2,5 wall is 79% thicker than the S5 wall, and wall thickness is what you are paying for.

What each supplier assumes when you leave a field blank

There is a second-order consequence worth naming. When you compare unnormalised quotes and award to the lowest, you systematically select the supplier who made the thinnest assumptions. Repeat that across a few purchase orders and your range drifts toward the lightest wall in the market without anyone deciding that it should. The buyer did not choose a thinner product; the blank fields chose it.

The fix is not more questions. It is a line item that leaves nothing to interpretation, followed by a way of grading the answers you get back. That is the rest of this page.

Fix the pipe line item: OD, series and the class that governs both

A PP-R line item that produces comparable quotes carries five things: outside diameter, pipe series (or its SDR equivalent), the application class paired with the design pressure, the material construction, and the length or coil format. Miss the middle three and you are back to comparing assumptions.

The dimensional numbers to quote back at your supplier

These are the minimum wall thicknesses the standard sets for dimension class A. Put the series in your request and the wall follows automatically; put only the OD and it does not.

Minimum wall thicknesses in millimetres, EN ISO 15874-2:2013 Table 5, dimension class A. Note that the outside diameter is bounded on both sides — a nominal 20 mm pipe must measure between 20 and 20,3 mm, so an undersized OD is as much a rejection as an oversized one.

The wall thickness behaves differently, and this is the detail most buyers miss. Its tolerance is written in the form +x mm — plus only. For a minimum wall above 2,0 and up to 3,0 mm the tolerance is +0,4 mm; from 3,0 to 4,0 mm it is +0,5 mm. There is no negative allowance at all. A caliper reading below the table minimum is not a pipe at the bottom of its range; it is a non-conforming pipe, and that is the sentence to put in your inspection clause. The tolerance level corresponds to Grade V in ISO 11922-1.

Why a bare PN number is an incomplete specification

Quotes routinely say “PN20” or “PN25” and stop. That is half an answer, because in the standard the allowable series depends jointly on the design pressure and the application class — the service duty the system will actually see. For PP-R at a design pressure of 10 bar, the maximum calculated S value is 3,0 for application Class 1, 2,1 for Class 2, 3,3 for Class 4 and 1,9 for Class 5. At 6 bar the same four classes permit 5,0, 3,5, 5,5 and 3,2.

The same pressure figure licenses a materially different wall depending on the duty, because the design stress differs by class: 3,02 MPa for Class 1, 2,12 MPa for Class 2, 3,29 MPa for Class 4 and 1,89 MPa for Class 5, all against a design coefficient of 1,5 at operating temperature.

You do not need to run that calculation. You need to force the supplier to state the class alongside the pressure, and to state it the way the standard itself marks it. One more constraint applies regardless of series: pipe intended to be joined by heat fusion must carry a minimum wall of 2,0 mm. On small diameters in the thinnest series that floor, not the series table, is what governs.

Grade the answer, not the brochure: what a real supplier reply contains

Every checklist on the internet tells you to ask about lead time, capacity and certification. None of them tells you how to mark the answer. That is the part that decides the award, because a fluent supplier and a capable supplier write very similar first emails. The difference is always the same: a capable answer names the constraints that could make it wrong.

Lead time

A bare number is unusable. “Thirty days” does not say thirty days from what — your enquiry, your deposit, your artwork approval, or the moment their extruder is free. It does not say whether shipping is inside or outside the window, and ocean booking alone can move a delivery date by more than a week regardless of how fast the pipe was made.

• Substantive: “Thirty days ex-works, counted from artwork sign-off, with moulds already in hand and 20 mm held in stock. The booking window to your port is separate and we quote it when the sailing schedule is confirmed.”
• Evasive: “Around 30 days, sometimes faster.”
• What separates them: the first names a start event, a dependency and an exclusion. The second is a hope. Ask which event starts the clock and what would push it — a supplier who runs a production schedule answers immediately; one who is buying from a third party has to go and ask.

Minimum order quantity

MOQ is rarely a single figure, and a supplier who quotes one without qualification is usually quoting a container. The real structure is per size, per colour, per print run, or per container — and the constraint that bites is often tooling or artwork, not volume.

• Substantive: “No MOQ on standard stock items; a mixed pallet is fine. Custom print carries a minimum per size because the print run has a setup, and a new mould has its own minimum. Tell us the size mix and we will tell you which lines trigger which minimum.”
• Evasive: “MOQ is negotiable.”
• What separates them: the first distinguishes stock from customisation, which is the actual mechanism. “Negotiable” tells you only that a number exists and they would rather you did not know it yet.

Whether they extrude or resell

This one you cannot ask directly and expect a useful answer, because everybody says factory. Ask process questions instead — ones only a producer can answer without leaving the desk: which grade of resin the standard line runs and who supplies it; how OD, wall and ovality are recorded during a run; whether the print line can carry a customer’s own designation and what the setup involves.

• Substantive: “We run a named compound grade from a named producer; OD and wall are logged at set intervals through each run against the S-series table and the records stay with the batch. Custom print needs a plate change, so it has a setup and a minimum.”
• Evasive: “We use only 100% virgin raw material and advanced German equipment with strict quality control.” Followed by photographs of a production hall.
• What separates them: the first describes records, intervals and a physical constraint. The second describes adjectives. A trader answers the commercial questions fluently and the process questions slowly, or with a photograph instead of a record — because a photograph is the only production artefact they have.

Read the print line before you read the certificate

Certificates arrive as PDFs and take a week to verify. The print line arrives on the sample and takes thirty seconds, and it is a compliance record in its own right — EN ISO 15874-2:2013 specifies exactly what must appear on the pipe. Check the sample against this list before you spend effort on the document set.

The last row is the one that decides how a future dispute goes. Without a production period and, where the maker runs more than one plant, a site code, a failure eighteen months from now cannot be traced to a run — which means it cannot be quantified, bounded, or credited. Suppliers who mark properly are not being fastidious; they are protecting themselves as much as you.

Then do the cross-check that catches most substitutions. The print line, the quote and the sample must all agree on the same three numbers: OD, wall and class-with-pressure. A quote that says one thing and a sample that says another is not a translation error, and it should be resolved before an order, not after a container. Note also which edition you are dealing with — the PP-R pipe part in force is the 2013 edition, amended in 2018, and a supplier still citing the 2003 edition is telling you something about how recently their documentation was reviewed.

Ask for the certificate set by scope, issuer and validity

A logo wall proves nothing. Three questions turn a document set into evidence, and they work on any certificate from any body.

• What is the scope? Which product, which material construction, which size range. A credential covering solid-wall PP-R pressure pipe does not automatically extend to a fibre-reinforced or aluminium-composite wall, and it does not automatically cover the fittings.
• Who issued it? A certification body, a testing laboratory, and the manufacturer’s own declaration are three different things carrying three different weights.
• Valid until when? Approvals are revalidated on cycles. A scan with no reference number and no dates cannot be checked against anything.

Grade the reply the same way you graded lead time and MOQ. The three questions above are only useful if you know what a passing answer sounds like.

• Substantive: “The approval covers solid-wall PP-R pressure pipe, OD 20 to 110 mm; the fittings sit under a separate entry and the fibre-composite wall is not in scope. Here is the issuing body, the reference number and the revalidation date — look it up in the public directory. What we hold on the aluminium-composite line is a test report, not a certification, and I am telling you that before you ask.”
• Evasive: “We are fully certified — WRAS, SKZ, ISO. All certificates attached.” Followed by four PDFs with the reference numbers cropped or greyed out.
• What separates them: the first volunteers the boundary of its own coverage and hands you the means to check it. The second offers a logo count. The tell is scope: a supplier who knows which of their lines a credential does not cover has read the certificate; a supplier who answers with the names of bodies is reading the front page. Ask one question to force it — “which of these covers the fittings, and until when?” A real answer arrives in a sentence, because the person answering has the scope line in front of them.

Two distinctions buyers are routinely shown as one thing

The first is material approval versus product approval. WRAS states plainly that a Material Approval covers non-metallic materials and components — rubber sheet, O-rings and the like — tested only for their effect on water quality, demonstrating compliance with BS 6920. It is not an approval of the assembled fitting, and it is presented in supplier decks as though it were.

WRAS is an independent UK certification body accredited to ISO 17065, and it publishes a searchable directory holding more than 9,000 product ranges and 3,000 materials, so a claimed entry is checkable in a couple of minutes. Ask for the reference and look it up yourself. The approvals underpin compliance with the Water Supply (Water Fittings) Regulations 1999 in England and Wales, the equivalent Scottish Byelaws of 2014, and the Northern Ireland Regulations of 2009, so the relevant instrument depends on where the goods land.

The second is a laboratory test report versus a certification. A report says a sample tested on a date met a criterion. A certification implies ongoing surveillance of production. Both are legitimate and they answer different questions — the report tells you what a sample did, the certification tells you what the factory is held to. A supplier presenting a report as a certification is either careless with terms or counting on you being so, and either way it is worth one clarifying email.

Finally, match the pack to the destination, not to the longest list. Requirements are jurisdictional and vary by product type, application and the importer’s role, so the document set that clears one market may be irrelevant in the next. Where the stakes are high, confirm the current requirement with the local authority having jurisdiction or a customs broker rather than relying on a supplier’s summary. For a fuller treatment of what customs and an AHJ actually ask for, see the guide to importing PP-R pipe.

Packaging, marking and the Incoterm: the fields that move landed cost

Packaging is where a quote quietly stops describing what you will receive. It rarely changes the unit price and it reliably changes the landed cost, the warehouse labour and whether your own customers can buy a sensible quantity.

Fix the fields even when you do not yet know the values

You are not expected to specify a carton quantity. You are expected to require that one be stated, in writing, before you compare prices — because the supplier who quotes lower per metre and packs in loose bundles may cost you more once handling and breakage are counted.

• Pipe: length per piece, pieces per bundle, bundles per pallet, wrapping method, and whether ends are capped.
• Fittings: pieces per polybag, bags per inner carton, cartons per master carton, and the barcode or SKU marking on each level.
• Pallet: dimensions, gross and net weight, stacking limit, and whether pallets are heat-treated for the destination.
• Carton marking: what is printed on the outside — product code, quantity, batch, and your own reference if you need it for receiving.

The quantity-per-carton figure deserves special attention because it is the number your own sales team will live with. If your customers buy elbows in tens and the carton holds a hundred and twenty, every order breaks a carton and someone counts pieces by hand. That is a decision made once, at RFQ time, and then endured for years. For private label, add the artwork fields early: what is printed on the pipe itself, what appears on the carton, who supplies the files, and how a proof is approved — because as noted above, artwork sign-off is frequently the event that starts the production clock.

Name the Incoterm rule and the place

A price without a term is not a price. The ICC’s Incoterms 2020 set is the current edition, comprising eleven rules in a series that has been used in trade contracts since 1936. Two practical points follow for a PP-R order. First, always pair the rule with a named place — the rule allocates cost and risk at a point, and without the point the allocation is undefined. Second, four of the eleven are for sea and inland waterway transport only: FAS, FOB, CFR and CIF. Quoting FOB on a shipment moving by air or by truck is a category error, and it is common enough in first quotations that it is worth reading for.

Ask for the same rule from all three suppliers. If one insists on quoting differently, convert it yourself rather than comparing across terms — otherwise you are comparing a price that includes ocean freight with one that stops at the factory gate, which is the second most common reason quotes look 30% apart when they are not.

Packing and terms get the same grading treatment as the rest of the checklist, and the answers separate faster here than anywhere else, because these are figures a factory already knows and a reseller has to go and ask for.

• Substantive: “Four-metre lengths, ten pieces per bundle, twenty bundles per pallet, ends capped, pallet heat-treated. Elbows go fifty per polybag, ten bags per master carton, product code and batch printed on the master. Pallet gross weight and dimensions are on the packing sheet. Quoted FOB Ningbo — if you want it to your warehouse door say so and we will requote DAP with the place named.”
• Evasive: “Standard export packing. Price is FOB.” No carton quantity, no pallet basis, no named port.
• What separates them: the first states a quantity at every level and pairs the Incoterm rule with a place. The second uses “standard export packing” as a placeholder for figures nobody has counted, and quotes a rule with no point at which cost and risk actually change hands. Both gaps surface at the same moment — when the container is opened and the receiving team starts counting.

Worked comparison: normalising two quotes on the same 20 mm line

Here is the arithmetic, using only the dimensional figures above. The scenario is illustrative — it is a calculation you can repeat with your own quotes, not an account of a particular order.

You asked two suppliers for 20 mm PP-R pipe. Supplier A comes back cheaper per metre. Supplier B is dearer and has written “S3,2” on the line. Supplier A’s sheet says only “20 mm, PN20”. You measure the samples with a caliper: A’s wall is 1,9 mm, B’s is 2,8 mm.

Both are legitimate products. A is series S5 at the class-A minimum; B is series S3,2. The wall difference is 0,9 mm on a 20 mm pipe, which by the table above is the gap between the thinnest and the middle of the range — B is carrying 47% more wall. Once you notice that, A is not cheaper than B. A is a different product, and the two prices were never on the same axis.

Now check conformity before you draw any conclusion about value. Both walls sit at or above their respective table minima, and both clear the 2,0 mm fusion floor — except A does not: at 1,9 mm, series S5 at OD 20 is below the 2,0 mm minimum the standard requires for pipe intended to be joined by heat fusion. For a fusion-jointed PP-R system, A’s line is not a cheaper option; it is the wrong product, and this is the single check that most often resolves an inexplicable price gap.

Then apply the plus-only rule. Had A’s caliper read 1,8 mm against a declared S5, that pipe would be non-conforming outright, because the tolerance runs upward only.

Reissue the request with the series fixed and the class stated, and the two quotes land on one basis. What the comparison still cannot tell you is whether either supplier’s declared series is what arrives in month six. That is what the print line, the traceability marking and the certificate scope are for, and it is why the sample approval step belongs after a normalised quote rather than before it. If the divergence persists after normalising, the remaining variables are usually resin grade and fitting content — the virgin versus recycled question covers the first, and a factory audit covers what a document cannot.

How Hitze answers its own checklist, and where we stop

A checklist written by a supplier is worth reading only if the supplier will submit to it. Here are Hitze’s answers to the questions above, in the same format, including the three where the honest answer is that the figure is not published. The size and class figures below are the same ones published on the PP-R pipe and fittings range, so you can check the answers against the source rather than taking them from a table in an article.

Two of those rows say “not published”, and a third withholds numbers pending a request. That is deliberate. Under the currency rule this site works to, a credential is named with its scope and issuing body and nothing more — no certificate number, no implied expiry date — because no expiry date exists in any first-party record, and printing one would be inventing the very field this page tells you to demand.

What is checked in-house, and where the published record stops

The documented sequence behind those credentials has three stages, and it maps onto the same fields this checklist asks you to fix:

• Before extrusion: the resin is verified.
• During the run: outside diameter, wall thickness at multiple points, and ovality are checked against the S-series tables — the same tables reproduced earlier on this page.
• After production: pipes, fittings and fused joint assemblies are pressure-tested on in-house hydrostatic benches against DIN and EN ISO thresholds.

Where that record stops is worth stating as plainly as what it contains. Acceptance tolerances, reject rates and bench report references from those tests are not published. Apply your own rubric here: that is a scope answer without the numbers behind it, and the correct buyer response is to request the raw records for your batch rather than to accept the sequence as evidence.

For context on the entity behind the credentials: GERMANY Hitze INDUSTRY CO., LTD, founded 1974, operating a 120,000 m² production base with more than 1,000 employees and exporting to over 118 countries, with the trademark registered at the DPMA in Munich — which supports a German brand claim and not a “Made in Germany” origin claim. That distinction is itself a checklist item worth applying to any supplier trading on a European name.

Conclusion: the risk you carry is the field you left blank

The failure mode in PP-R sourcing is almost never a supplier who lied. It is a request that delegated four technical decisions to whoever was quoting, followed by an award that rewarded the most aggressive interpretation. Fix the series, pair the class with the pressure, require the packing basis and name the Incoterm with its place, and the quotes arrive comparable. Then grade the answers on whether they name their own constraints, read the print line before the certificate, and check any approval against the issuing body’s own directory rather than the deck.

One warning to carry forward. The specification you accept on a first order becomes the baseline for every reorder, and nobody re-examines it. If the first line item was vague, the vagueness compounds quietly across years of purchase orders until a batch fails somewhere expensive and there is no traceability marking to bound the exposure. Spend the extra hour on the request. If you are an importer or distributor building a PP-R range and want a quote issued on the normalised basis described here, that is the conversation to start.

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