Reading PEX Pipe and Fitting Markings Before You Join

Why this matters

Every PEX joint that lets go behind a finished wall was made with a tool and a fitting that looked right. The pipe and the fitting both tell you, in print, which joining system they were tested together under, and a tech who reads them takes thirty seconds. A tech who does not reads the color of the ring instead, and the color of the ring is not a standard. This card is how to read the print line on the pipe and the stamp on the fitting, and how those two readings pick the tool. The joining steps themselves live in their own HowTos.

The standard on the fitting names the joint, not the brand

PEX pipe is made to one material standard, ASTM F876 (the tube itself), and its system performance is tested under ASTM F877. The fittings are where the systems split. Each fitting standard describes a different way of holding the tube, and each one has its own tool, its own ring or sleeve, and its own check:

Push-to-connect fittings are a separate family listed to ASSE 1061, with no ring and no tool beyond a deburring and depth gauge. They show up on PEX, copper and CPVC alike, and their own marking tells you which tube types they accept.

Why the tool has to match the standard and not just the size. An F1807 copper ring is designed to be squeezed uniformly by jaws that close to a fixed diameter. An F2098 stainless ring is designed to be pinched at one ear. Put a crimp tool on a stainless clamp ring and it deforms the ring without making the clamp's designed bite; put a cinch tool on a copper ring and you get a pinch on one side and an open gap on the other. Both can hold test pressure for a day. Neither is the joint the listing was earned on, and the first thermal cycle on a hot line is where the difference shows.

The print line on the pipe

A PEX print line repeats every few feet. Read it near where you will cut, not off the end of the coil, because a repair often meets pipe from a different job. The order varies by maker; the content does not.

PIPE PRINT LINE (one repeat, broken to fit)

MAKER ID   1/2 CTS   SDR9   PEX-B   PEX 5306
   |         |        |       |        |
   brand     size     wall    method   material code

ASTM F876/F877   CSA B137.5   NSF-pw   NSF-rfh
       |              |          |        |
  tube + system   Canadian    potable  radiant

F1807  F2159  F2098      160 PSI 73F  100 PSI 180F
  |       |      |            |             |
 fitting systems listed   pressure at the two temps

LOT 2419-A   06/14/24   0412 FT
    |            |         |
 traceable     made     footage mark

FITTING STAMP (1/2 in brass elbow)

  [maker]  LF  1/2  F1807  NSF-61
           |   |     |      |
   lead-free   size  std    potable

Size and wall. Residential PEX is copper tube size (CTS), so 1/2 in nominal has a 5/8 in outside diameter, and SDR9 means the wall is one-ninth of the outside diameter. Fittings in the F1807, F2159, F2098, F1960 and F2080 families are made for SDR9 CTS tube. Imported or older tube sized to another dimension series exists, and an insert fitting in the wrong series feels loose or will not start. If the print does not say CTS and SDR9, stop and find out what it is.

Method letter. PEX-A, PEX-B and PEX-C describe how the polyethylene was crosslinked. The letter matters to the joint because cold expansion depends on the tube's ability to recover around the insert, which is why F1960 has traditionally been a PEX-A system. Some non-A tube is now listed for expansion fittings. The listing on the print is what counts, not the letter. See related: 'PEX-A vs PEX-B System Selection'.

The material designation code. The four digits after "PEX" in a code like 5306 are defined in ASTM F876. The first digit is the chlorine resistance class, and 5 is the class that covers continuous hot water recirculation at elevated temperature, the condition that kills lower-rated tube in a recirc system. The second digit is the UV exposure class, which tells you how long the tube may sit in sunlight before it is covered. The last two digits tie to the hydrostatic design basis. Read the first digit on any job with a recirculation pump, and the second on any job where tube sits in a framed but unroofed house.

The pressure ratings. Standard SDR9 PEX prints its rating at two temperatures, commonly 160 psi at 73 F and 100 psi at 180 F, and some tube adds 80 psi at 200 F. House pressure is capped at 80 psi static at the fixtures, so the cold rating is not the constraint. The hot rating matters next to a heater that is set high or a boiler loop. See related: 'The Pressure and Temperature Numbers on Every Residential Call'.

The listings. NSF-pw (or NSF 61 on a fitting) means the product is listed for potable water contact. NSF-rfh alone means radiant floor heating, not drinking water. A coil marked for heating only does not go on a domestic line, however much of it is on the truck.

The fitting systems. Many makers print every fitting standard their tube was tested with. That list is the menu of joints you may make on that tube. A standard that is not on the print is not on the menu.

Lot and date. Write the lot code into the ticket on any repair of a failed joint or a split tube. A manufacturer's claim starts with the lot, and the date also tells you whether the pipe predates a change in the maker's listings.

Reading the fitting and the ring

The fitting body carries its own stamp: the maker's mark, LF (lead-free, meaning it meets the federal low-lead limit for potable contact), the size, and the standard. Read that last item before you reach for a tool.

• Brass and copper inserts marked F1807 take copper crimp rings. Many are also marked F2098, which means they accept stainless clamp rings too.
• Plastic inserts (white, gray or tan polysulfone family) marked F2159 take copper crimp rings; if also marked F2098, stainless clamp rings.
• Expansion fittings have a larger insert with a raised shoulder and are marked F1960 or F2080. An F1960 fitting is used with a PEX ring; an F2080 fitting is used with a compression sleeve. They are not interchangeable even though both are "expansion."
• Rings and sleeves are their own component and must be the type the fitting standard names. A black copper crimp ring is a coated copper ring, not a different standard. A stainless ring with an ear is F2098 whatever it looks like next to the copper ones in the bin.

The worked case: a repair where the truck carries the wrong system

A service call: a 1/2 in hot line under a kitchen sink split at a kink where the cabinet base was pushed back. The house is 2012 construction. The truck carries expansion fittings and an expansion tool, plus a box of F1807 brass crimp fittings and copper rings with a crimp tool and gauge.

Step one, isolate before you cut. The split is upstream of the sink stop, so close the heater's cold supply, which stops the hot side, and open a hot tap at another fixture to relieve the pressure; a tap downstream of a closed stop relieves nothing upstream of it. The water in the line is still near 120 F and the tube pushes out what it holds when cut, so wear gloves and eye protection and keep your face out of line with the cut while you are under the cabinet.

Step two, read the print within a foot of the cut. The tube reads: MAKER ID, 1/2 CTS, SDR9, PEX-B, PEX 5306, ASTM F876/F877, NSF-pw, F1807 F2159 F2098, 160 PSI 73F, 100 PSI 180F, and a 2012 date code.

Step three, compare the menu to the truck.

• F1960 is not on the print, so the expansion fittings are out on this tube, even if they could be forced onto it.
• F1807 is on the print, and the truck carries F1807 brass couplings with copper rings. That is a listed joint.
• F2098 is also on the print, so a stainless clamp would be listed too, but there is no clamp tool on the truck.

Step four, check the tool against the ring. The crimp tool's jaws are for 1/2 in copper rings, and its go/no-go gauge was checked on a test crimp at the start of the week. Make one test crimp on an offcut and gauge it before the repair crimps go on.

Step five, make the repair and record it. Cut out the kink, install a coupling with two copper rings, gauge both crimps, then restore water: open the heater cold supply, bleed air at the kitchen hot tap and the tap you opened, and watch the joint at full house pressure for a few minutes before closing the cabinet. The ticket gets the lot code, the fitting standard used, and the gauge result on both crimps.

What would change the call. If the tube had printed PEX-A with F1960 and F1807, either system on the truck would have been listed, and the choice becomes access: an expansion joint needs room to rotate the tool and time for the tube to recover, and a crimp needs room for the jaws to close square. If the print had listed only F1960 and F2080, the crimp fittings would have been off the menu, and the right move is a trip for the right fitting rather than a crimp on tube that was never tested with one. If the print is unreadable, cut out enough tube to reach a legible repeat, or treat the tube as unknown and replace the run back to a fitting whose system you can identify.

What this card deliberately leaves out

Ring color. Shops talk about "black rings" and "the silver ones" as if color were a standard. It is a finish. Two rings of the same color can belong to different standards, so the shop's bins should be labeled by standard, not by color.

The brand-system question. Code asks that pipe and fittings be listed to the standards in the adopted edition's pipe and fitting tables (IPC 2021 Chapter 6, as adopted; IRC 2021 Chapter 29, as adopted; UPC 2021 Chapter 6, as adopted). A coupling from one maker on tube from another is generally acceptable to the code where both carry the same fitting standard. Whether the tube maker's warranty survives it is a separate question answered by that maker's warranty terms, and some makers do condition coverage on their own fittings. Read the warranty on jobs where it will matter.

Tool calibration. Gauging a crimp, checking a cinch tool, and inspecting expansion heads are steps in the joining procedures. See related: 'How to Make PEX Crimp and Clamp Joints and Check Them' and 'How to Make a PEX-A Cold Expansion Joint'.

How to verify you read it right

• You can name the fitting standard on the fitting, find the same standard in the pipe's print, and point to the tool that standard requires. Any one of the three missing means the joint is not made yet.
• The pipe print includes NSF-pw or NSF 61 on every piece of a potable line, including the short stub you are joining to.
• On a recirculating hot system the material code's first digit is 5.
• The lot code and the standard used are on the ticket for every repair.

References

• ASTM F876 and F877 (PEX tube and PEX system performance), and ASTM F1807, F2159, F2098, F1960 and F2080 (PEX fitting systems), in the editions referenced by your adopted code
• ASSE 1061 (push-fit fittings)
• NSF/ANSI 61 (drinking water system components) and the NSF-pw listing mark
• See related: 'PEX-A vs PEX-B System Selection'
• See related: 'PEX Installation Procedure Reference'