Common Plumbing Fittings Reference
Overview
Quick-reference for the fittings techs encounter on residential service work. Different materials use different fittings; mis-matching creates leaks. This is the on-truck identification card.
Reference Table
Copper fittings:
| Fitting | Use | Joining method |
|---|---|---|
| 90° elbow (street + standard) | Direction change | Solder OR press (ProPress, Viega) |
| 45° elbow | Gentler direction change | Solder OR press |
| Tee | Branch | Solder OR press |
| Coupling | Joining same-size pipe | Solder OR press |
| Reducer / bushing | Size change | Solder OR press |
| Cap | End closure | Solder OR press |
| Union | Removable joint | Threaded faces, no solder |
| Adapter (MIP / FIP) | Copper-to-threaded transition | One side solder, other threaded |
PEX fittings:
| Fitting | Joining method | Notes |
|---|---|---|
| Crimp / cinch fittings | Brass barbed insert + crimp ring | Most common residential PEX |
| Expansion fittings (PEX-A) | Brass insert + expansion tool | Uponor / Wirsbo system |
| Push-fit (SharkBite, etc.) | Push the pipe in, internal grab ring | Easy install but premium-priced |
| Stab-fit reducers / couplings | Same as push-fit | For mixing material sizes |
PVC + CPVC fittings:
| Fitting | Joining method | Notes |
|---|---|---|
| Schedule 40 PVC fittings | Solvent welding (purple primer + cement) | Drain + cold supply |
| CPVC fittings | Solvent welding (CPVC-specific cement, beige) | Hot + cold supply |
| Threaded transitions | Threaded with Teflon tape | Connecting to threaded valves |
| Compression couplings | Hand-tighten + 1/4 turn | Removable repair joints |
Cast iron + ABS (legacy DWV):
| Fitting | Joining method |
|---|---|
| Cast iron fittings | Lead + oakum OR no-hub clamps (modern) |
| ABS DWV fittings | ABS solvent cement (black; chemical-specific) |
| PVC-to-cast-iron adapter | Heavy rubber transition + clamp |
Specifications - sizing conventions
Nominal vs actual size: pipe size labels reference the INSIDE diameter (nominal). The outside diameter is larger. A "1/2 in copper" pipe is ~5/8" OD, not 1/2". Always match fittings to the nominal size.
Common residential sizes:
| Use | Pipe size |
|---|---|
| Supply branches to fixtures | 1/2" |
| Main supply trunks | 3/4" or 1" |
| Toilet branches | 1/2" |
| Lavatory drain | 1-1/4" or 1-1/2" |
| Tub / shower drain | 1-1/2" |
| Kitchen sink drain | 1-1/2" or 2" |
| Toilet drain | 3" |
| Main building drain | 3" or 4" |
| Vent stacks | 1-1/2" to 2" |
Notes
- NEVER mix solvent cements. PVC cement on CPVC creates joints that look good but fail under heat. CPVC cement on PVC similar issue. Verify before applying.
- Push-fit fittings (SharkBite + similar) are removable. This makes them ideal for repair situations + temporary connections. They're also code-approved in most jurisdictions for permanent installs, but some inspectors still prefer soldered or pressed joints for in-wall applications.
- Press fittings on copper are fast + reliable but require a press tool. Common in commercial; gaining traction in residential.
- Solder vs braze: solder for water supply (lead-free 95/5 tin-antimony or similar). Braze for refrigerant or gas lines. Don't substitute.
Lead-based solder is BANNED for potable water supply by federal law since 1986. Verify any solder reels in your truck are clearly marked "lead-free." Old reels from older techs may still be lead-bearing; using them on a residential potable line is a serious code violation + a health hazard.
References
- IAPMO Uniform Plumbing Code, Chapter 6 (Water Supply) + Chapter 7 (Sanitary Drainage)
- Manufacturer fitting catalogs (Charlotte Pipe, Mueller, Viega, Uponor)
- Manuall internal: Pipe Size & Material Reference, Annual Whole-Home Plumbing Inspection