4.1.8 Student Book © 2004 Propane Education & Research CouncilPage 1 4.1.8 Selecting Piping and Tubing After completing the gas customer profile and examining

4.1.8 Student Book © 2004 Propane Education & Research Council Page 1

4.1.8Selecting Piping and

Tubing

After completing the gas customer profile and examining construction drawings, you are ready to apply code requirements and equipment sizing methods to produce the system layout and materials specifications.

In this module you will learn to identify:(1) NFPA code requirements for vapor distribution systems(2) Characteristics and applications for piping and tubing

materials (3) Sizing methods for buried distribution lines (4) Sizing methods for distribution lines on half-pound systems (5) Distribution lines requirements for 2-pound systems


NFPA Code Requirements for Vapor Distribution Systems

NFPA 58

2004

NFPA 54

2002

Two primary codes are used in designing propane distribution systems:

1. NFPA 58, LP-Gas Code, covering the propane supply container(s), the first and second-stage regulators, and the connecting distribution lines between the regulators

2. NFPA 54, National Fuel Gas Code, covering gas piping systems from the outlet of the second-stage or 2-PSI service regulator, into the building, and to installed gas appliances



2nd Stage o r2 P SI S e rv iceR egu la to r

1s t StageR egu la to r

N F PA 5 4N ation a l F ue lG as C od e

N F PA 5 8L P -G as C od e

Figure 1. The Dividing Line for Applying NFPA 58 and NFPA 54

4.1.8 Student Book © 2004 Propane Education & Research Council Pages 2 & 3


NFPA 58 requirements for piping and tubing are found:

Topic

2.4.2 Piping Materials 5.8.3.1

2.4.3 Tubing Materials 5.8.3.2

2.4.4 Fittings 5.8.4

NFPA 58

2001

NFPA 58

2004

4.1.8 Student Book © 2004 Propane Education & Research Council Pages 3 - 5


NFPA 54 requirements for piping and tubing are found:

NFPA 54

2002

Materials and installation requirements for building piping system components are found in

Chapter 5: Gas Piping System Design, Materials, and Components

Chapter 6: Gas Piping Installation.


Characteristics of Piping and Tubing Materials

Steel Pipe is durable, widely available, and very economical for use inside homes and businesses. Steel pipe is not a proper choice for piping runs in concealed spaces that require joining methods that are not accessible in the event of a leak or required piping modification.

Figure 2. Steel Pipe



Copper Tubing Copper tubing is a highly flexible material often used as the buried distribution line. In small vapor distribution systems, copper tubing is economical and relatively simple to install.

Unprotected copper tubing should not be used in wall partitions or other locations that potentially subject it to puncture by nails, screws or other fasteners.

Installers must exercise care when flaring copper tubing. If a flare is made that contains splits or other imperfections, is too large or too small for the flare nut, it must be cut off, and a proper flare made.

Because flared copper tubing joints are metal-to-metal formed seals, personnel must know not to use pipe thread sealing compounds and how to properly tighten brass fittings to assure gas-tight joints in copper lines without splitting the tubing or flare nut.



Polyethylene (PE) Tubing is increasingly used for buried distribution lines, especially with underground tank installations. It does not contribute to galvanic corrosion of underground tanks.

Figure 3. PE Tubing & Mechanical Fitting of Anodeless Riser



Polyethylene (PE) Tubing— Service Limitations

PE tubing must be:

1. Installed underground with a minimum burial depth of 18 inches below grade or other protection must be provided if the minimum 18 inch depth cannot be attained

2. Used in propane vapor service only and not subject to operating pressures in excess of 30 psig

3. Terminated by the use of an approved protective riser where PE emerges from the ground in the form of an anodeless riser or field-assembled service head adapter

4. Provided a buried insulated electrical wire or conductive locating and warning tape installed above the tubing for the purpose of tracing and locating the buried PE tubing



Polyethylene (PE) Tubing— Special Considerations

Persons who install PE tubing and fittings should be qualified by the manufacturer, supplier, or qualified trainers, and be thoroughly familiar with manufacturer written joining and installation procedures.

Persons who make repairs of PE distribution lines that have been in service must be familiar with the ignition source hazard that PE pipe and tubing create due to static electricity, and should know and apply proper excavating and grounding methods to apply before and during repair operations.

They should also use appropriate personal protective equipment, ignition prevention, and fire control measures throughout PE distribution repair operations.



2nd -Sta g e o r2-PSI Se rvic eRe g ula to r

Se rvic e He a dAd a p te r

Ano d e le ssRise r

1st Sta g eRe g ula to r

PE Tub ing

Lo c a ting Wireo r C o nd uc tiveTa p e

Figure 4. Buried Polyethylene Tubing and Associated Fittings



Figure 5. CSST and Fittings

Corrugated Stainless Steel Tubing (CSST) is widely used in new construction and modifications to existing vapor distribution systems. CSST is typically used in 2-PSI systems, but if properly sized, may be used for relatively short runs in half-pound systems.



Corrugated Stainless Steel Tubing (CSST)— Special Considerations:

CSST can be used in 2-PSI systems or half-pound systems.

Installers should be qualified by CSST manufacturers, suppliers, or qualified trainers and thoroughly familiar with the manufacturer’s installation procedures and instructions.

Special carbon steel protective devices or plates are required to protect CSST where it is concealed, constrained from moving, or routed to areas within 3 inches of locations subject to puncture strikes.



Figure 6.In-Wall Sleeve Seal

Figure 7.In-Slab Installation of CSST

for an Island Appliance


Sizing Methods for Buried Distribution Lines

The term “pipe sizing” means the selection of the diameter of pipe or tubing which must be used.

When sizing buried distribution lines select the diameter of pipe (or tubing) needed to deliver an hourly Btu load of gas for a specific distance with a loss of pressure of not more than 0.5 psig.



Polyethylene (PE) Piping/Tubing — System Components

2nd Sta g eRe g ula to r Se rvic e He a d

Ad a p te rG a s Rise r

1st Sta g eRe g ula to r

PE Tub ing

Lo c a tin g W ireo r C o n d uc tiveTa p e

Figure 8. Polyethylene Tubing Buried Distribution Line for a Two-Stage System




Figure 9. Anodeless Riser with Stab Connector

Figure 10. Cutaway View of PE Inside Coated Steel




Figure 11. Closer Cutaway View of “Stab” Mechanical Connector Fitting

Figure 12. Field Assembled Service Head Adapter

Used Here for Transition to 1st Stage Regulator




Figure 13. Installing Insulated Locater Wire

Figure 14. Locater Tape in Trench Above PE



Polyethylene (PE) Piping/Tubing — To properly size a PE buried distribution line, the length of the line from the outlet of the gas riser to the inlet of the service head adapter must be measured. Add one foot for “snaking” the tubing in the trench.

Figure 15. PE Tube Sizing Table 9.33

NFPA 541999



Polyethylene (PE) Piping/Tubing —

Figure 16. Two-Stage Appliance

Distribution System

26 Feet

First StageRegulator

Water Heater38,000 Btuh

Clothes Dryer35,000 Btuh

Range65,000 Btuh

Furnace200,000 Btuh

58 Feet

a1

a3

a 2

f

e

b

c

g

h

d

Total run is: 26 feet Total system demand is: 338,000 Btuh Use: ½” CTS PE



Copper Tubing — Sizing is done in a similar manner to PE; just use the appropriate sizing chart from NFPA 58 or 54.

Figure 17. Copper Tube Sizing Table 9.27

Total run is: 26 feet Total system demand is: 338,000 Btuh Use: ½” Type L

NFPA 541999


Sizing Methods for ½-Pound Distribution Lines

The inner surfaces of all piping or tubing resist the flow of propane, thus slowing it down and reducing its pressure as it passes through. This friction loss is commonly known as pressure drop.

The term pipe sizing means the selection of the diameter of pipe or tubing which must be used.

When sizing pipe, the service person selects the diameter of pipe needed to deliver an hourly Btu load of gas for a specific distance with a loss of pressure of not more than a specified amount, such as 0.5" water column in the 10.5 to 11 inches w.c. sections of a half-pound system.



According to NFPA 54 the following factors must be considered:• Allowable loss in pressure from point of delivery to

equipment burner • Maximum gas demand • Length of piping and number of fittings • Specific gravity of the gas • Diversity factor • Foreseeable future demand



Using Capacity Tables

Step 1: Locate the applicable fuel gas capacity table by name or by specific gravity (1.50 for propane; 0.60 for natural gas).

Step 2: Verify the application (“Special Use” or run description) for the table. See illustration below this step.

Step 3: Locate the length of the piping run (for example, if the run is 58 feet, use the next larger table length entry, 60).




Step 4: Trace across the row to locate the Btu capacity needed for the pipe run that is equal to or greater than the load required (for example, if the load is 338,000 Btuh, the closest number shown below for 60 foot runs is 434,000).

Step 5: Trace up the column to the metallic pipe size required (1 inch nominal inside diameter).






Diversity Factor Diversity factor is a comparison of the maximum probable demand (Btuh) to the maximum possible demand 9Btuh) and is expressed as a fraction or ratio:

Diversity Factor =Maximum Probable Demand

Maximum Possible Demand

The use of a diversity factor is not recommended unless the fraction is greater than 1. If it is less than 1, because a diversity factor is an estimate, it does not reflect actual conditions in the piping system, and its use can lead to selection of piping which is not of sufficient size to handle full appliance demand.



Sizing Distribution Lines for Half-Pound Systems Using a 1st & 2nd-Stage Regulator—To determine the sizes of piping or tubing required for the two-stage propane gas installation in Figure 19 use the following method:

Figure 19. Two-Stage Propane Gas Installation



Step 1: Determine the total gas demand for the system by adding the Btuh input from the appliance nameplates and the demand as appropriate for future appliances.

Step 2: Measure the length of piping required from outlet of first regulator to the inlet of the second regulator.

Step 3: Measure the length of piping required from outlet of second regulator to the appliance farthest away (Longest Run Method).

Step 4: Make a simple sketch of the piping.

Step 5: Determine the capacity to be handled by each section of piping.



Step 6: Using the appropriate tables from NFPA 54, select the proper tubing or pipe size for each section of piping, using values in Btuh for the length determined from steps #2 and step #3. If the exact length is not on the table, use the next longer length. Do not use any other length for this purpose! Simply select the size that shows at least as much capacity as needed for each piping section.


Sizing 2-PSI System Distribution Lines

Distribution lines in 2-PSI systems use smaller diameters in the 2-PSI sections of the system compared to half-pound (11 inches water column) distribution systems.

A number of different distribution layouts can be used in 2-PSI systems. Examples using different line materials and line regulator locations are illustrated on the following pages.



Furnace125,000 Btuh

Water Heater36,000 B tuh

Dryer28,000 B tuh

CSST 2-PSI Pressure System

Range52,000 B tuh

ManifoldR

2-psi ServiceRegulator

Line Regulator

A = 20 ft

B = 10 ft

C = 30 ft

D = 30 ft

E = 25 ft

Figure 20. 2-PSI Single Manifold Distribution System

Example 1



Example 1: Method for Single Line Regulator Systems with No Branched Runs Off a Single Manifold

Step 1: Determine the total gas demand for the system. Use this value to determine the size of the “trunk line” (A) running between the outlet of the 2-PSI service regulator and the line regulator.

Step 2: Determine the tubing diameter needed for each single-appliance line section using the Btuh input of the appliance and the length of CSST needed to connect the appliance to the manifold.

Step 3: Use the “Longest Run Method” for sizing the appliance lines in the branched runs (E, F, and G).



Example 1: Method for Single Line Regulator Systems with No Branched Runs Off a Single Manifold



Figure 21. 2-PSI Single Manifold with Branched 11” w.c. Line

Example 2

Furnace125,000 Btuh


Grill25,000 B tuh

CSST 2-PSI Pressure System

Range52,000 B tuh

ManifoldR


Line Regulator

A = 20 ft

B = 10 ft

C = 30 ft

D = 30 ft

F = 15 ft

G = 10 ft

E = 25 ft

Dryer28,000 B tuh



Example 2: Method for Single Line Regulator Systems with a Branched Run Off the Manifold

Step 1: Determine the total gas demand for the system. Use this value to determine the size of the “trunk line” (A) running between the outlet of the 2-PSI service regulator and the line regulator.

Step 2: Determine the tubing diameter needed for each single-appliance line section using the Btuh input of the appliance and the length of CSST needed to connect the appliance to the manifold.

Step 3: Use the “Longest Run Method” for sizing the appliance lines in the branched runs (E, F, and G).






Figure 22. 2-PSI Branched Lines & Multiple Manifold Layout

Example 3Furnace

80,000 B tuh

Dryer28,000 B tuh

CSST 2-PSI M ultip le M anifold System

Range52,000 B tuh

M anifoldR

M anifoldR

Line Regulator

Furnace60,000 B tuh


Fireplace45,000 B tuh


Line Regulator

B = 40 fee t

A = 20 fee t





Step 1: Determine the total gas demand for the system. Use this value to determine the size of the “trunk line” (A) running between the outlet of the 2-PSI service regulator and the line regulator. Use the “longest length” in the trunk line section (A + B) to size both trunk lines.

Step 2: Determine the total gas demand served by trunk line B. Use the “longest length” in the trunk line section (A + B) to size both trunk lines.

Step 3: Determine the tubing diameter needed for each single appliance line section using the Btuh input of the appliance and the length of CSST needed to connect the appliance to the manifold.




Although CSST distribution lines were used for Examples 1-3 illustrating 2-PSI systems, remember that steel pipe and copper tubing can be used in 2-PSI systems as well. Some system designs may call for a combination of these materials. Regardless of the materials used in the piping runs, be sure that the correct sizing methods and capacity charts are used when determining the diameter for each type of material used, and its place in the distribution system.

4.1.8 Student Book © 2004 Propane Education & Research Council Pages 25 - 28

Time to See If You Got the Key Points of This Module…

• Complete the Review on pages 25 & 26.

• See if you are ready for the Certification Exam by checking off the performance criteria on page 27 & 28.

Documents

4.1.8 Student Book © 2004 Propane Education & Research CouncilPage 1 4.1.8 Selecting Piping and Tubing After completing the gas customer profile and examining