Pipe Sizing

What affects gas pressure loss in a pipe?

Density of the gas affects pressure losses in pipe

What is the max allowable pressure into a residential building?

2 psig

Where do you find the correct gas pressure for an appliance?

On the appliance rating plate or as specified by an engineer

What materials are used for gas lines and how does code vary?

Gas line materials can be pipe or tubing; code differs for each

Can reused gas piping be used?

Yes, if cleaned

What pipe schedules are used for gas line pressure ranges?

Low pressure uses Schedule 40 (150 psig rating); NG or propane up to 125 psig needs at least Schedule 10 (indoors for 1/2" to 2", Schedule 40 for larger sizes); commercial/industrial often uses Schedule 80

What are key requirements for copper tubing in gas lines?

Most common gas tubing, must be brazed, flared, or compression-fitted (double ferrule); no soldering; Type K approved for underground without resin covering

Where and how is plastic gas tubing allowed?

Only HDPE (polyethylene) is approved; outdoor underground only; cannot be used for liquid propane or near vaporizer/temps above 50°C; requires 14AWG tracer wire along length; must transition to steel riser

What are hose requirements for gas appliances?

Min working pressure 350 psig; no slip-on fittings (must use crimp); length limits: permanent install max 10ft, construction heaters 15-75ft, portable BBQ max 30ft, IR heaters must be 36"wc ±6"; can't pass through walls or exceed 50°C

What is CSST and what testing does it need?

Corrugated stainless steel tubing (Gastite is a brand); factory tested at 100 psig so field testing isn't needed, but still requires onsite system pressure test after installation

What factors affect low pressure gas line design?

Fuel type, pipe length, flow capacity, material, branch loads, obstacles, and max allowable pressure drop

Who owns gas piping up to the meter in Canada?

Utility company

What does Table A.16 in B149.1 cover?

Resistance to flow from fittings, expressed as equivalent straight pipe length

How is the "Longest Run" defined for pipe sizing?

Distance from piping start point to farthest pressure change point in system, including equivalent fitting lengths from Table A.16

What tables help size valves in gas code?

Annex A, Annex B, and Table A.16 for fitting equivalents

What is the 50ft rule for shutoff valves on gas manifolds?

Shutoff valves must be tagged and within 50ft of the appliance they serve (Clause 6.18.2, d)

How do you size for header vs branch?

Header sizing is based on total appliance input beyond longest run point (peak demand); branch sizing is based on individual appliance load, but always use the longest run length for table lookup

What is good practice for gas piping layout design?

Draw a rough isometric sketch showing fuel type, longest run, pipe type, total BTU load, supply pressure, and allowable pressure drop

What is the smallest pipe size allowed for NG and propane?

Natural gas threaded pipe: minimum 1/2" (unless Schedule 80); Propane: minimum 3/8" for single appliance under 25ft

How is gas volume for sizing determined?

From appliance rating plate or manufacturer data

What are the allowable pressure drops for pipe sizing?

Natural Gas: Max 1"wc drop for 7-14"wc supply; Propane: Max 1"wc drop for 11"wc supply; High-pressure gas: Max 50% of gauge pressure drop

What are extension options if the existing line isn't large enough?

Install larger main line at meter outlet or run a parallel branch within 2ft of meter outlet; meter capacity may need upsizing

What are key steps for designing a high pressure gas line?

Know supplier and meter location, review blueprints, site visit to check for obstacles, add fitting losses to run length, draw isometric layout

What gas code tables cover high pressure piping?

Tables A1-A4 and A8-A11 include engineered fitting factors; Tables A5-A7 and A12 do not (you must calculate fitting equivalent lengths with Table A16)

What is STP (Standard Temperature and Pressure)?

15°C and 14.7 psia

How is gas supply sized for high pressure systems?

For maximum appliance demand unless diversity is allowed by local authority

How do you calculate longest run for every pressure zone?

After every regulator, start a new longest run calculation

What happens if pipe size must increase after fitting allowance?

You must also upsize fittings and re-do the allowance until both pipe and fittings meet requirement

When can you skip Table A16 for fitting allowances?

If using a limited number of fittings

What key CSA B149.1 points relate to gas line sizing?

Appliance gas volume from rating plate or manufacturer info (Clause 6.4.2)

Additions under 20ft or welded tie-ins are exempt from Table 6.3 (Clause 6.22.4)

Schedule 40 threaded pipe OK up to 125 psig (Clause 6.2.3)

Hose/fittings need 350 psig minimum rating (Clause 6.2.10)

Natural rubber cannot be used for gaskets (Clause 6.9.7)

Gas line at 10"wc must limit pressure loss to under 1"wc (Clause 6.3.2)

Max commercial propane pressure is 20 psig (mechanical rooms/rooftop); industrial also 20 psig

Max propane construction heat pressure allowed into building is 25 psig

Which pressures do not need the fitting allowance (equivalent pipe length based on fitting pressure loss) calculation because they are already roughly included in the calc?