Journeyman Plumber cheat sheet

The IPC and the UPC are the two most widely adopted model plumbing codes; the locally adopted edition plus local amendments is what is enforceable, and the authority having jurisdiction (AHJ) interprets it.

Horizontal drainage pipe slopes a minimum of 1/4 inch per foot for sizes 2-1/2 inches and smaller, and 1/8 inch per foot for 3-inch through 6-inch pipe.

A trap must maintain a liquid seal between 2 and 4 inches deep, measured from the trap weir to the top of the dip.

Vent pipe may not be smaller than 1-1/4 inches nominal and must be at least one-half the diameter of the drain it serves.

Cleanouts are required at the base of each stack, at the upper end of horizontal drains, at intervals not exceeding 100 feet, and at changes of direction greater than 135 degrees.

A vent must not be installed within two pipe diameters of the trap weir (crown venting), and double trapping and S-traps are prohibited.

Vent terminals must extend at least 6 inches above the roof surface and be kept at least 10 feet from doors, openable windows, and outdoor air intakes, and 3 feet above any forced-air inlet within 10 feet.

Concealed work such as underground drains, rough-in piping, and gas piping must be inspected and approved before it is covered.

One drainage fixture unit (DFU) represents approximately 1 cubic foot per minute of probable discharge, or about 7.48 gallons per minute.

Common fixture unit values: water closet 3 (flush tank) or 4 (flushometer), lavatory 1, bathtub 2, shower 2, kitchen sink 2, dishwasher 2, washing machine 2, floor drain 1.

Trap arm developed length from the trap weir to the vent fitting is limited to roughly 5 feet for 1-1/4 inch, 6 feet for 1-1/2 inch, 8 feet for 2 inch, 12 feet for 3 inch, and 16 feet for 4 inch.

A vent must rise vertically at least 6 inches above the flood level rim of the fixture before any horizontal offset, except where wet venting or stack venting is specifically permitted.

The building drain runs from the inside face of the building wall to a point 30 inches outside the building; beyond that point the same pipe is the building sewer.

Use a sanitary tee or combination fitting where flow turns from vertical to horizontal, and a wye or combination where flow turns from horizontal to horizontal.

A backwater valve is required where a fixture's flood level rim is below the elevation of the next upstream manhole cover on the sewer.

Vent types include individual, common, wet, stack, circuit, and island (loop) vents; an air admittance valve may only be substituted where the adopted code permits it.

Static pressure in a potable water distribution system is limited to 80 psi; where street or main pressure exceeds that, a pressure-reducing valve must be installed.

A minimum residual pressure is needed at fixtures: typically 8 psi for standard fixtures and much higher flowing pressures (roughly 15 to 35 psi) for flushometer valves.

Water velocity is normally kept between about 5 and 8 feet per second; higher velocities cause noise, erosion, and excessive pressure loss.

Backflow protection options include air gaps, reduced-pressure-zone assemblies, double-check valve assemblies, pressure vacuum breakers, and atmospheric vacuum breakers, chosen by degree of hazard.

A closed system protected by a backflow preventer or check valve needs a thermal expansion tank to absorb the volume increase as water is heated.

Fixture unit demand is converted to gallons per minute using Hunter's curve; a lavatory is typically 1 fixture unit and about 1 gpm of demand.

Water hammer arrestors are installed near quick-closing valves such as flushometers, solenoids, and washing machine valves to absorb the pressure surge.

Common distribution materials are copper types K, L, and M, PEX, CPVC, and PEX-AL-PEX; underground service pipe is buried below the local frost depth.

Maximum flow rates: water closet 1.6 gallons per flush (1.28 gpf is common today), urinal 1.0 gpf, showerhead 2.5 gpm at 80 psi, kitchen and lavatory faucets 2.2 gpm, public lavatory faucets about 0.5 gpm.

A water closet requires at least 15 inches from its centerline to any side wall or partition and at least 21 inches of clear space in front of the bowl.

A water closet compartment is at least 30 inches wide and 60 inches deep; an accessible water closet seat is set 17 to 19 inches above the floor.

Accessible counters are a maximum of 34 inches high (36 inches where the approach is not parallel) with knee and toe clearance below.

Each fixture must have a trap with a 2 to 4 inch seal, and the fixture outlet must be above the trap weir so the trap cannot be double-trapped.

Floor drains in areas subject to sewer gas or evaporation require trap primers to maintain the seal.

Indirect waste connections, such as ice machine or food service drains, require an air gap or air break and may not be directly connected to the drainage system.

Faucet and fixture outlets must terminate above the flood level rim of the receptor to provide an air gap against backflow.

A temperature and pressure relief valve is typically rated at 150 psi and 210 degrees F and must be installed in the top 6 inches of the storage tank.

The relief valve discharge pipe must be full size, flow by gravity, contain no valves or traps, and terminate not more than 6 inches above the floor or outside the building.

Recovery in gallons per hour equals input BTU per hour times efficiency, divided by 8.33 times the temperature rise.

Storage water heaters are commonly set to 120 degrees F for scald prevention, or 140 degrees F with a tempering (mixing) valve at the point of use.

A gas-fired water heater installed in a garage must have its ignition source elevated at least 18 inches above the floor.

A drain pan at least 1-1/2 inches deep with a piped drain is required where a leak would cause damage to the structure or finished space.

Seismic strapping uses two straps, one in the upper third and one in the lower third of the tank, fastened to the structure.

Typical manifold pressures are about 3.5 inches water column for natural gas and 10 to 11 inches water column for propane; appliance inlet pressure may not exceed 14 inches water column (1/2 psi).

A sediment trap (drip leg) is installed downstream of the appliance shutoff valve, as close as practicable to the appliance inlet.

The manual shutoff valve must be in the same room as the appliance and within 6 feet of it.

Gas pipe is sized by the longest-length method, using total BTU load and equivalent length of fittings to select pipe diameter from code tables.

A vent connector needs at least a 12-inch vertical rise before the first elbow, slopes upward at 1/4 inch per foot toward the chimney, and its lateral run is limited relative to the vertical rise.

Clearance to combustibles is typically 6 inches for single-wall vent connectors and 1 inch for listed Type B double-wall vent.

An unconfined space needs about 50 cubic feet of volume per 1,000 BTU per hour of total input, or free grille area of 1 square inch per 1,000 BTU per hour split evenly between high and low openings.

Corrugated stainless steel tubing (CSST) is bonded to the grounding electrode system with a minimum 6 AWG copper conductor.

Gas piping is pressure-tested with air or inert gas before being placed in service, and leaks are located with soap solution or an electronic detector, never with a flame.

OSHA requires a protective system (sloping, benching, shoring, or a trench box) for any excavation 5 feet deep or greater unless it is solid rock.

In trenches 4 feet or deeper, a ladder or other means of exit must be within 25 feet of lateral travel for workers.

Spoil and materials are kept back at least 2 feet from the edge of an excavation to prevent cave-in.

Portable ladders follow the 4-to-1 rule (base 1 foot out for every 4 feet of height) and extend 3 feet above the landing surface.

Call 811 before digging so underground utilities can be located and marked, generally at least two to three working days in advance.

Required PPE includes eye protection, gloves, hard hat, and hearing or respiratory protection matched to the task; hot work requires a fire extinguisher and a fire watch after the work is complete.

Pipe wrenches are pulled, not pushed, and two wrenches are used (one to hold, one to turn) so joints elsewhere in the assembly are not loosened.

Lockout/tagout procedures are followed before servicing electrical equipment, and permit-required confined spaces require atmospheric testing and an attendant.

At a scale of 1/4 inch = 1 foot, one inch on the drawing equals 4 feet in the field; convert by multiplying the measured drawing distance by 4.

Total fall equals slope multiplied by run: a 1/4 inch per foot slope over 20 feet produces 5 inches of fall.

For a 45-degree offset, travel equals offset times 1.414 and offset equals travel times 0.707; for 22-1/2 degrees the travel factor is 2.613, and for 60 degrees it is 1.155.

One psi equals 2.31 feet of water column, and each foot of elevation adds 0.433 psi of static pressure.

Heat load in BTU per hour equals gallons per minute times 500 times the temperature difference.

One gallon occupies 231 cubic inches; pipe volume per foot in gallons equals pi times the inside radius squared times 12, divided by 231.

One drainage fixture unit is roughly 7.5 gallons per minute, and one cubic foot equals 7.48 gallons.

Invert elevation equals rim or grade elevation minus the depth of cover, and the invert of a downstream pipe is set by subtracting the fall from the upstream invert.