Basic Plumbing Fittings Guide Cheat Sheet: Essential Components for Repairs & Projects

Introduction

Plumbing fittings connect pipes and components in water supply, drainage, and gas systems. This comprehensive cheat sheet covers common plumbing fittings, their applications, and essential information for identifying and using them in DIY repairs and installations.

Pipe Types & Common Materials

Common Pipe Materials

• PVC (Polyvinyl Chloride): White plastic pipe for cold water drainage
• CPVC (Chlorinated PVC): Cream/yellow plastic pipe for hot/cold water supply
• PEX (Cross-linked Polyethylene): Flexible colored plastic tubing for water supply
• Copper: Rigid metal pipe for water supply and gas lines
• Galvanized Steel: Gray metal pipe for water supply (older homes)
• ABS (Acrylonitrile Butadiene Styrene): Black plastic pipe for drainage
• Cast Iron: Heavy black metal pipe for drainage (older homes)
• PE (Polyethylene): Black plastic pipe for gas, water mains

Pipe Size Designations

• Nominal pipe size: The approximate internal diameter
• Actual dimensions: Often differ from nominal size
• Common residential water supply sizes: 1/2″, 3/4″, 1″
• Common residential drain sizes: 1-1/4″, 1-1/2″, 2″, 3″, 4″

Basic Fitting Types & Their Uses

Couplings

• Purpose: Connect two pipes of the same diameter in a straight line
• Types:
  • Straight coupling: Basic same-diameter pipe connection
  • Reducing coupling: Connects pipes of different diameters
  • Slip coupling: No internal stop, allows for repair without cutting precise lengths
  • Compression coupling: Uses rubber gaskets to seal without solvent welding
• Applications: Extending pipe runs, repairing damaged sections

Elbows (Ells)

• Purpose: Change direction of pipe run
• Common angles: 90° (quarter bend), 45° (eighth bend), 22.5°
• Types:
  • 90° elbow: Creates right-angle turn
  • 45° elbow: Creates moderate angle turn
  • Street elbow: Has one male and one female end
  • Sweep elbow: Gradual curve for better flow (drainage)
  • Drop ear elbow: Includes mounting tab for securing to structure
• Applications: Navigating corners, changing pipe direction

Tees

• Purpose: Create branch line from main pipe run
• Types:
  • Straight tee: All openings same diameter
  • Reducing tee: Branch opening smaller than main run
  • Bullhead tee: Main line smaller than branches
  • Street tee: One male end, two female ends
• Applications: Splitting water lines, creating branch connections

Wyes (Y-Fittings)

• Purpose: Create 45° branch from main pipe run
• Types:
  • Standard wye: Same diameter for all openings
  • Reducing wye: Branch opening smaller than main line
  • Double wye: Two 45° branches from main line
• Applications: Drainage systems where gradual flow is important

Unions

• Purpose: Allow future disconnection of pipes without cutting
• Types:
  • Threaded union: Joins threaded pipes with threaded nut
  • Copper union: For joining copper pipes
  • Plastic union: For joining plastic pipes
• Applications: Points where future disassembly may be needed (pumps, filters)

Caps & Plugs

• Purpose: Seal off end of pipe
• Types:
  • Cap: Female fitting that fits over pipe end
  • Plug: Male fitting that fits inside pipe opening
  • Test cap: Temporary cap used during pressure testing
• Applications: Terminating lines, future expansion points, testing

Adapters

• Purpose: Connect different types of pipes or fittings
• Types:
  • Male adapter: Pipe threads on outside (MIP/MPT)
  • Female adapter: Pipe threads on inside (FIP/FPT)
  • Slip x thread: Connects slip fitting to threaded component
  • Material transition: Connects different pipe materials
• Applications: Connecting to threaded components, transitioning materials

Bushings & Reducers

• Purpose: Connect pipes of different diameters
• Types:
  • Bushing: Short reducing fitting, often threaded
  • Reducer: Connects different size pipes
  • Bell reducer: Larger opening has bell shape
  • Concentric reducer: Centers remain aligned
  • Eccentric reducer: Bottom remains aligned (prevents air traps)
• Applications: Transitioning between pipe sizes

Flanges

• Purpose: Connect pipes to fixtures or appliances
• Types:
  • Toilet flange: Connects toilet to drain pipe
  • Floor flange: Secures pipe to floor
  • Drop ear flange: Includes mounting tabs, for faucets
  • Blind flange: Solid plate to seal end of flanged pipe
• Applications: Fixture connections, securing pipes to structures

Specialized Drainage Fittings

Traps

• Purpose: Create water seal to prevent sewer gases from entering building
• Types:
  • P-trap: P-shaped, standard for sinks
  • S-trap: S-shaped (often not code-compliant in new installations)
  • Bottle trap: Compact design for tight spaces
  • Drum trap: Larger reservoir (older installations)
• Applications: Under sinks, tubs, showers

Cleanouts

• Purpose: Provide access for cleaning/unclogging drains
• Types:
  • Threaded cleanout plug: Basic access point
  • Cleanout tee: Tee with access port
  • Cleanout wye: Wye with access port
  • Floor cleanout: Flush with floor surface
• Applications: Drain line maintenance points

Closet Bends/Closet Flanges

• Purpose: Connect toilet to drain line
• Types:
  • 90° closet bend: Right angle connection
  • Offset closet flange: For off-center drains
  • Adjustable flange: Height-adjustable for various floor coverings
• Applications: Toilet installations

Specialized Water Supply Fittings

Valves

• Purpose: Control water flow
• Types:
  • Ball valve: Quarter-turn operation, full flow
  • Gate valve: Multi-turn operation, not for frequent use
  • Globe valve: Multi-turn operation, regulates flow
  • Angle valve: Changes direction 90° while controlling flow
  • Check valve: Allows flow in one direction only
• Applications: Shutoffs, flow control, backflow prevention

Manifolds

• Purpose: Distribute water from single source to multiple lines
• Types:
  • PEX manifold: For PEX tubing systems
  • Copper manifold: For copper pipe systems
  • Compression manifold: Uses compression fittings
• Applications: Radiant heating, multi-fixture water distribution

Pressure Regulators

• Purpose: Reduce water pressure to safe levels
• Types:
  • Direct-acting: Spring-loaded design
  • Pilot-operated: For precise regulation
• Applications: Whole-house pressure reduction, appliance protection

Specialty Fittings

Dielectric Fittings

• Purpose: Prevent galvanic corrosion between dissimilar metals
• Types:
  • Dielectric union: Separates dissimilar metals
  • Dielectric nipple: Threaded pipe with insulation
• Applications: Connecting copper to galvanized steel

Expansion Fittings

• Purpose: Accommodate thermal expansion/contraction
• Types:
  • Expansion coupling: Allows pipe movement
  • Expansion loop: Configured pipe run that flexes
• Applications: Long pipe runs subject to temperature changes

Escutcheons

• Purpose: Cover wall penetrations for aesthetic finish
• Types:
  • Split plate: Can be installed without disconnecting pipe
  • Solid plate: Must slide onto pipe before installation
  • Hinged: Opens to install around existing pipe
• Applications: Where pipes penetrate finished walls

Connection Methods & Materials

Threaded Connections

• Materials: Brass, steel, some plastic
• Connection method: Screw together with pipe dope or Teflon tape
• Tools needed: Pipe wrenches, thread sealant
• Application notes: Don’t overtighten; use thread sealant appropriate for application

Solvent Weld (Glued)

• Materials: PVC, CPVC, ABS
• Connection method: Apply primer (if required) and cement, push together
• Tools needed: Primer, appropriate cement, clean cloth
• Application notes: Joint must be made quickly; follow cure times before pressurizing

Soldered/Brazed

• Materials: Copper, brass
• Connection method: Clean, flux, heat, apply solder
• Tools needed: Torch, solder, flux, emery cloth, wire brush
• Application notes: Ensure all water is removed from pipe; don’t overheat

Compression

• Materials: Various, primarily for copper, PEX, CPVC
• Connection method: Tighten nut to compress ferrule/ring
• Tools needed: Adjustable wrenches or pliers
• Application notes: Good for repairs and tight spaces; don’t overtighten

Push-to-Connect

• Materials: PEX, copper, CPVC
• Connection method: Push pipe into fitting until it seats
• Tools needed: Pipe cutter, deburring tool
• Application notes: Ensure clean, straight cut; insert pipe fully

Crimped/Clamped

• Materials: PEX primarily
• Connection method: Place ring over pipe, insert fitting, crimp/clamp ring
• Tools needed: Crimping/clamping tool specific to system
• Application notes: Follow manufacturer’s specifications exactly

Flanged

• Materials: Cast iron, steel, some plastic
• Connection method: Bolt together with gasket between
• Tools needed: Wrenches, gaskets, bolts
• Application notes: Tighten bolts in alternating pattern

Common Fitting Measurements & Terminology

Thread Types

• NPT (National Pipe Thread): Tapered, standard for plumbing
• NPS (National Pipe Straight): Straight threads, for mechanical connections
• NPSM (National Pipe Straight Mechanical): Straight threads with mechanical seal
• BSP (British Standard Pipe): Used in some imported fixtures

Thread Designations

• MIP/MPT: Male Iron Pipe/Male Pipe Thread (external threads)
• FIP/FPT: Female Iron Pipe/Female Pipe Thread (internal threads)
• MIPT: Male Iron Pipe Thread
• FIPT: Female Iron Pipe Thread

Size Notation

• Nominal size: Approximate interior diameter of pipe (e.g., 1/2″)
• Actual dimensions: Physical measurement (varies by material)
• OD: Outside Diameter
• ID: Inside Diameter

Code Considerations & Best Practices

Common Code Requirements

• Proper materials: Use approved materials for application
• Support spacing: Support pipes at code-specified intervals
• Slope requirements: Drain pipes need proper slope (typically 1/4″ per foot)
• Trap requirements: Every fixture needs properly installed trap
• Cleanout access: Required at specific locations in drainage system
• Venting: All drain fixtures must be properly vented

Best Practices

• Use quality materials: Don’t compromise on fitting quality
• Follow manufacturer instructions: Especially for specialty systems
• Allow clearance: Provide access for maintenance and repairs
• Test before closing walls: Pressure test water lines, leak test drains
• Label shutoffs: Mark valves for future reference
• Document installation: Take photos before covering work

Troubleshooting Fitting Issues

Leaks at Fittings

• Threaded connections: Tighten moderately; if still leaking, disassemble, clean, apply new sealant
• Solvent-welded joints: Cannot be repaired; must be cut out and replaced
• Soldered joints: Try additional solder if accessible; otherwise cut out and replace
• Compression fittings: Tighten slightly; if continues, replace ferrule/O-ring
• Push-to-connect: Ensure pipe fully inserted; use disconnect tool to remove and inspect

Incompatible Materials

• Galvanic corrosion: Use dielectric unions between dissimilar metals
• Material transitions: Use appropriate transition fittings
• Temperature limitations: Ensure fittings rated for temperature of application
• Pressure ratings: Verify fittings meet system pressure requirements

Tools for Working with Fittings

Essential Tools

• Pipe cutters: For clean, straight cuts
• Pipe wrenches: For threaded connections
• Adjustable wrenches: For nuts and bolts
• Channel-lock pliers: For holding and turning
• Thread sealant: Tape or paste for threaded connections
• Tubing cutters: For copper and plastic tubing
• Deburring tools: Remove sharp edges after cutting

Specialty Tools

• PEX crimping/clamping tools: For PEX connections
• Soldering equipment: Torch, solder, flux
• Pipe threading dies: For creating threads on pipes
• Press fitting tools: For press-connect fittings
• Basin wrench: For accessing fittings in tight spaces

Shopping Guide & Tips

Selecting Fittings

• Material compatibility: Match to existing pipes
• Pressure rating: Meet or exceed system requirements
• Temperature rating: Appropriate for application
• Size verification: Double-check measurements
• Quality indicators: Weight, material consistency, markings

Where to Buy

• Home centers: Good selection of common fittings
• Plumbing supply houses: Wider selection, professional advice
• Online retailers: Access to specialty items
• Salvage/reuse centers: For matching older systems

Cost-Saving Tips

• Buy common fittings in bulk: Especially for large projects
• Consider multi-packs: Often cheaper per unit
• Compare material costs: PEX often cheaper than copper
• Avoid emergency purchases: Keep essential repair fittings on hand

Safety Considerations

Working with Different Materials

• PVC cement: Use in well-ventilated area, avoid skin contact
• Solder/flux: Protect against burns, provide ventilation
• Galvanized pipe: Can release zinc dust when cut
• Old pipes: May contain lead or asbestos in insulation

General Safety

• Turn off water: Always shut off before starting work
• Verify gas lines: Never work on gas lines without proper knowledge
• Proper PPE: Gloves, eye protection
• Know limitations: Call professionals for complex work
• Permits: Obtain when required by local codes

Remember, this cheat sheet provides general guidance. Always consult local building codes and manufacturer instructions for specific requirements in your area. When in doubt, consult a licensed plumber for complex installations or repairs.