How a Moulded PP-R Fitting Is Traced: Cavity Numbers, Lot Codes and the COO Declaration

Most traceability advice for PP-R assumes a print line, and a moulded fitting does not have one. A PP-R fitting is traced by reading three marks together. The cavity number moulded near the gate names the piece of mould steel that formed it, the production-period mark dates it, and the lot code on the bag or carton label ties it to a moulding run and a resin lot. ISO 15874-3:2013 requires only four aspects on the fitting body, and none of them is a cavity number or a lot code. Country-of-origin marking is a separate duty, set by the import market.

The date insert described below is easier to understand turning than on paper. This short clip from DME, a maker of mould components rather than pipe or fittings, shows a dual-ring date insert; it is general moulding hardware, not a PP-R fitting mould.

Why a moulded fitting has no print line

Pipe is extruded as one continuous length, so its marking is printed inline, and ISO 15874-2:2013 requires it not less than once per metre. Our sister site’s guide to reading the print line on a PP-R pipe covers that line field by field.

An elbow is formed one shot at a time, usually in a mould with several cavities running side by side. Anything moulded into the part is cut into the steel, so every shot from that cavity carries identical text until someone changes an insert. Fitting marks can say which cavity and roughly when, never which shot; the link to a run and a resin lot lives on the packaging. Clause 11.1 of ISO 15874-3 still requires marks printed or formed directly on the fitting, legible without magnification after storage, handling and installation.

What ISO 15874-3 requires on the fitting, and what can go on the label

ISO 15874-3:2013 Table 10 requires four aspects on the fitting itself: the manufacturer’s name or trade mark, the nominal diameter, the material and the traceability information. Everything else may be marked on the fitting or put on a label supplied with the fittings. The traceability information is the production period, year and month, in figures or in code, plus a name or code for the production site when the manufacturer produces at different sites. “In code” matters: a two-digit stamp or a letter-number pair is compliant, but only readable with the supplier’s key. Ask for that key with the first sample, not after the first claim, and file it with the purchase order.

Source: ISO 15874-3:2013, clause 11 and Table 10; 19 U.S.C. 1304. Status column reflects the 2013 text; confirm against the amended table in your edition.

Table 10 asks for no cavity number, mould number, lot code or country of origin. A compliant supplier can ship parts you cannot trace past the month, so extra marks belong in your purchase specification. ISO 15874-3 also carries Amendment 1:2018 and Amendment 2:2021 and is flagged by ISO as “to be revised”, so check the amended Table 10 in your licensed edition before copying it into a spec. Our PP-R fittings catalogue shows the socket, elbow, tee and transition shapes these marks are moulded on.

Reading cavity numbers and date inserts

Cavity numbers

The cavity number is usually a small raised or sunken digit near the injection point. Beaumont’s David Hoffman, writing in Plastics Engineering, recommends placing cavity IDs as close to the gate as possible and not on ejector pins, because pins get moved during maintenance and the history is lost. A cavity ID on an ejector pin is a warning in itself: the number on your failed part may no longer match the steel it came from.

Date inserts

The production period usually comes from a date insert, the clock-face circle with a year in the centre and an arrow pointing at a month; stamps run 3 to 20 mm across, most often 6 to 12 mm. Plastics Technology notes that date stamps can indicate the year, month, day, shift and batch, and that they are updated by turning the centre arrow. Someone has to turn it. An insert still reading last year’s month, on a carton labelled this year, means the setter skipped a step; ask what else the start-up checklist missed.

One cavity or all of them

Read the two marks together once a defect appears. Hoffman attributes variation within a flow group of cavities to steel and variation between flow groups to viscosity. In buyer terms, failures clustered on one cavity number point at the mould; failures spread across every cavity point at material or process. Those are different conversations with the supplier: the first ends in a mould repair and a cavity blocked off, the second in a resin certificate and the run’s test records.

Tracing one failed elbow back to a resin lot

A trace only works if the importer kept the link the fitting cannot carry. A 2022 study in Polymers reports that PP shows a low ability to absorb near-infrared radiation at 1064 nm, a standard marking-laser wavelength, so the lot code normally goes on a removable adhesive label. Once the bag is emptied into a van bin, the lot code is gone.

1. Photograph the failed part before anyone cleans it: cavity number, date insert and fracture face in one frame.
2. Find the bag or carton label from the same delivery and record the lot code and the date on it.
3. Ask the supplier for the moulding record behind that lot: machine, mould, cavities running, shift, resin lot and the pressure-test result for the run.
4. Quarantine stock from the same lot, and if the failure sits on one cavity, the parts from that cavity first.
5. Compare the answer with the pattern: one cavity means steel, every cavity means material or process.

The minimum record an importer keeps is short: purchase order, lot codes received per SKU, a scan of the carton labels, and which project or customer each lot went to. Without the last column a recall becomes a letter to every customer. Ask in writing how long the factory keeps its side of the record.

What we check, and where we stop

Hitze pressure-tests pipes, fittings and fused joint assemblies on in-house hydrostatic benches against DIN and EN ISO thresholds. The quality control page shows where those checks sit, and the lot code is what connects a bench result to the carton in your warehouse. Where we stop: this page prints no Hitze lot-code format or record-retention period. Both are confirmed per order, in writing, against the list in the conclusion.

Country of origin: marking and declaring moulded fittings

United States

Origin marking is not a pipe-standard question, and the most common mistake is borrowing the metal rule. Section 1304(c) of 19 U.S.C. requires die stamping, cast-in-mold lettering, etching, engraving or continuous paint stenciling of the country of origin, but it names iron, steel and stainless steel pipe and steel, stainless, chrome-moly and cast or malleable iron pipe fittings. A plastic fitting falls under the general rule in 1304(a): marked in a conspicuous place as legibly, indelibly and permanently as the nature of the article will permit.

Source: 19 U.S.C. 1304; 19 CFR 134.1; European Commission, non-preferential origin; EU Combined Nomenclature 2026, heading 3917. Tariff headings and origin rules are revised periodically; confirm them against current CBP guidance and the CN edition in force before filing.

Section 1304(a)(3) excepts an article that is incapable of being marked, cannot be marked before shipment without injury, cannot be marked except at an economically prohibitive expense, or whose container marking will reasonably indicate its origin. Those are case-by-case decisions, not a blanket licence to mark only cartons. The mark must reach the ultimate purchaser, generally the last person in the United States who will receive the article in the form in which it was imported (19 CFR 134.1(d)). Get it wrong and 1304(i) levies an additional duty of 10 percent ad valorem.

European Union and brass-insert fittings

For the EU, the European Commission applies the last substantial transformation test. In a mixed container, pipe and fittings are separate declaration lines, so a fitting moulded in one plant and pipe extruded in another each carry their own origin. Brass-insert fittings deserve a written answer, because the insert may come from a different plant and where origin lands is a customs determination; our guide to US pipe import clearance covers the ruling route. Brand wording is a separate matter: Hitze is a German brand, engineered in Germany, and never labelled “Made in Germany” without origin evidence.

Lead time and what to confirm before you order

Ask what drives the date before asking for the date. Four things decide it for a moulded fitting: whether the size runs on an existing mould, how many cavities that mould runs, whether brass inserts must be sourced, and when the run’s pressure testing is scheduled. Your own brand, a new cavity-numbering scheme or a site code on the part means a new or modified mould insert, which adds tooling time before the first shot. Lot code, origin wording or a barcode change only the label. Hitze has no minimum order quantity and quotes lead time per order, so request the lead time per SKU with and without your marking changes, in writing on the proforma.

Conclusion

Before the first container, confirm six things in writing:

• the four ISO 15874-3 body marks, checked on a sample;
• whether cavity numbers and a date insert are moulded, and where;
• which label carries the lot code, and in what format;
• the moulding record the supplier can produce per lot, and for how long;
• origin wording, and whether it goes on the part or the carton, per market;
• the lead time per SKU with and without your marking changes.

With those answered, a failed elbow traces to a lot, a cavity and a resin batch. Verify the first four on a real part with our PP-R sample approval checklist.

Frequently asked questions