All entries A to Z

52 entries · Updated October 29, 2026

Every entry in Know Your Pipes, alphabetically, with a one-line description. Entries are also grouped by category.

A

ABS pipe: Black acrylonitrile butadiene styrene drain, waste and vent pipe; solvent-cemented with ABS cement and used much like white PVC DWV.

B

Black steel gas pipe: Threaded Schedule 40 steel pipe with a dark finish, long used for natural gas and propane piping inside buildings.
Brass fittings and dezincification: Brass is a copper-zinc alloy used for valves and fittings; dezincification is corrosion that removes its zinc.
Burst pipe: first steps: The order of priorities when a water pipe bursts: water off at the main, electricity safety, then a licensed plumber.

C

Cast iron drain pipe: Gray iron soil pipe for drain, waste, vent and sewer lines, made in hub-and-spigot and hubless (no-hub) forms.
Compression fittings: Threaded fittings that seal when a nut squeezes a brass or plastic sleeve onto the tube; common at supply stops and on small tubing.
Copper DWV pipe: Hard copper drainage tube made to ASTM B306 for drain, waste and vent lines, identified by a yellow print line.
Copper pipe types K, L and M: The three wall grades of copper water tube under ASTM B88, how to tell them apart and where each is normally used.
Copper press fittings: Copper or bronze fittings with a rubber sealing element, crushed onto copper tube by a powered press tool; made to ASME B16.51.
CPVC pipe: Rigid chlorinated PVC water pipe in copper tube sizes, rated 100 psi at 180°F and joined with CPVC solvent cement.
CSST gas tubing: Flexible jacketed stainless steel gas tubing; yellow CSST must be bonded to the electrical grounding system against lightning damage.

D

Dielectric unions: The insulated union that joins copper to galvanized or other steel pipe to slow galvanic corrosion, and why it can still fail.

F

Fitting shapes: elbows, tees, couplings: The basic shapes of pipe fittings, what each one does, the drain-fitting bend names, and the socket, spigot and thread end codes.
Frozen pipes by material: How PEX, CPVC, PVC and copper behave when the water inside them freezes, and why no pipe is freeze-proof.

G

Galvanized steel pipe: Zinc-coated steel water pipe found in older homes; it corrodes from the inside and can hold lead from upstream sources.

H

Heat-fusion joints: How socket, butt, saddle and electrofusion joints melt PP-R or polyethylene pipe into one piece; temperatures and standards.

I

Identifying the pipes in your house: Color, scratch, magnet and print-line clues that tell lead, galvanized steel, copper, PEX, CPVC, PVC and ABS apart.

K

Kitec pipe: Multilayer plastic-aluminum water pipe with brass fittings made by IPEX; its fittings were prone to dezincification and leaks.

L

Lead pipe and lead service lines: Soft gray lead water pipe, mostly in service lines; how to recognize it and what EPA's 2024 rule requires of water systems.
Lead-free solder: Solder and flux with no more than 0.2% lead, the only kind allowed on US drinking-water plumbing since 1986.

N

No-hub couplings: The neoprene-sleeve, stainless-shield coupling that joins hubless cast iron drain pipe: standards, torque and transition types.
Nominal pipe size, CTS and IPS: Why pipe sizes are names rather than measurements, and how the CTS and IPS outside-diameter systems differ for the same nominal size.
NSF/ANSI 14 (plastics piping): The NSF standard for plastic pipe, fittings and related materials, and what its pw, dwv and other end-use marks mean.
NSF/ANSI/CAN 372 (lead content): The standard used to certify plumbing products to the federal 0.25% lead-free limit, and how to read its marks.
NSF/ANSI/CAN 61: The health-effects standard for products that touch drinking water: what NSF 61 tests, what it covers and where codes require it.

O

Orangeburg pipe: Bituminous fiber sewer pipe made of tar-soaked fibers, laid from about the 1950s to early 1970s; it deforms, cracks and lets roots in.

P

PEX clamp (cinch) rings: Stainless steel bands with a tab, closed by a ratcheting tool over PEX insert fittings; an ASTM F2098 alternative to copper crimp rings.
PEX crimp rings: Copper rings squeezed around PEX over a ribbed insert fitting; made to ASTM F1807 or F2159 and checked with a go/no-go gauge.
PEX expansion fittings: Fittings joined by stretching PEX tubing and a ring, then letting the tube shrink back onto the fitting; ASTM F1960 and F2080.
PEX pipe: Flexible cross-linked polyethylene tubing for hot and cold water, rated 100 psi at 180°F and joined with mechanical fittings.
PEX-A pipe: PEX tubing cross-linked by the peroxide (Engel) method during extrusion; the type used with cold-expansion fittings.
PEX-B pipe: PEX tubing cross-linked by the silane (moisture-cure) method; commonly joined with crimp, clamp, press or push-fit fittings.
PEX-C pipe: PEX tubing cross-linked by an electron beam after the tube has been extruded.
Pinhole leaks in copper pipe: Small leaks in copper water tube caused by pitting corrosion, and the water, flow and workmanship factors linked to them.
Pipe sizing basics for houses: How water supply pipe sizes for a house are chosen: code minimums, flow, velocity and pressure, and why the job belongs to a plumber.
Plumbing codes: IPC, UPC and IRC: The three main US model plumbing codes, who writes them, what each covers and how states and cities adopt them.
Polybutylene pipe: Gray, flexible plastic water supply pipe used in US homes from the late 1970s; leaks and class actions ended its use.
Polyethylene water service pipe: Flexible black or colored PE tubing buried between the water main or well and the house; cold water only.
PP-R pipe: Polypropylene random-copolymer pressure pipe, joined by heat fusion, used for plumbing and hydronic systems mostly in larger buildings.
Push-fit fittings: Fittings that seal by pushing tube into an O-ring and locking device; covered by ASSE 1061 for PEX, copper, CPVC and PE-RT.
PVC DWV and foam-core pipe: White PVC drain, waste and vent pipe, made solid-wall (ASTM D2665) or with a lighter cellular foam core (ASTM F891); drainage only.
PVC Schedule 40 pipe: White rigid PVC pipe made to ASTM D1785; used for cold-water pressure lines outside the house and, when dual-marked, for drains.
PVC Schedule 80 pipe: Dark gray, thick-wall PVC pressure pipe; same outside diameter as Schedule 40 but a smaller bore and higher pressure rating.

R

Reading the print line on pipe: What the printed or stamped text along PEX, copper and plastic pipe means: size, standards, ratings, listings and date.

S

Sanitary tees and wyes: How sanitary tees, wyes and combination wyes differ, and which drain direction changes each fitting is allowed to make.
Shutoff valves: The valves that stop water in a house: ball, gate and fixture stop valves, how they differ, and the rules that apply to them.
Soldered (sweat) joints: How a sweat fitting is soldered to copper tube by capillary action, which solders are lawful for drinking water, and how brazing differs.
Solvent-weld joints: How solvent cement fuses PVC, CPVC and ABS pipe into fittings, the matching cement and primer standards, and set and cure times.
Sunlight and UV limits for plastic pipe: What sunlight does to PVC, CPVC, ABS and PEX pipe, how long PEX may be exposed, and how outdoor runs are protected.

T

Threaded pipe joints: How NPT tapered pipe threads seal, common sizes and pitches, thread sealants, and why plastic female threads crack.
Transition fittings: Adapters, couplings and unions that join pipes of different materials or size systems, from CPVC-to-brass to plastic-to-cast-iron.

W

Which pipe for which job: A job-by-job guide to the pipe materials used for water supply, service lines, drains, vents and gas, with their main limits.