4.2.19 student book © 2004 propane education & research councilpage 1 4.2.19 performing...

4.2.19 Student Book © 2004 Propane Education & Research Council

4.2.19

Performing Pressure Tests on Gas Distribution

Lines

Gas personnel must understand how to perform pressure tests on gas distribution lines to ensure the system is gas tight.

In this module you will learn to identify:

(1) NFPA 54 regulations that apply to pressure testing of a propane distribution system

(2) Basic elements of pressure testing

(3) Procedures commonly used to pressure test propane piping

4.2.19 Student Book © 2004 Propane Education & Research Council

NFPA 54 Regulations that Apply to Pressure Testing

NFPA 54

2002

7.1.4.1 Test pressure shall be measured with a manometer or with a pressure measuring device designed and calibrated to read, record, or indicate a pressure loss due to leakage during the pressure test period. The source of pressure shall be isolated before the pressure tests are made. Mechanical gauges used to measure test pressures shall have a range such that the highest end of the scale is not greater than 5 times the test pressure.

7.1.4.2 The test pressure to be used shall be no less than 1-½ times the proposed maximum working pressure, but not less than 3 psi, irrespective of design pressure.

7.1.4.3 Test duration shall be not less than ½ hour for each 500 cubic feet of pipe volume or fraction thereof. When testing a system having a volume less than 10 cubic feet or a system in a single-family dwelling, the test duration shall be a minimum of 10 minutes. The duration of the test shall not be required to exceed 24 hours.

4.2.19 Student Book © 2004 Propane Education & Research Council Pages 1 & 2


NFPA 54

2002

7.1.1.3 Where repairs or additions are made following the pressure test, the affected piping shall be tested. Minor repairs and additions are not required to be pressure tested provided that the work is inspected and connections are tested with a non-corrosive leak-detecting fluid or other leak-detecting methods approved by the authority having jurisdiction.

7.1.1.4 Where new branches are installed from the point of delivery to new appliance(s), only the newly installed branch(es) shall be required to be pressure tested. Connections between the new piping and the existing piping shall be tested with a non-corrosive leak-detecting fluid or approved leak-detecting methods.

7.1.1.5 A piping system shall be tested as a complete unit or in sections. Under no circumstances shall a valve in a line be used as a bulkhead between gas in one section of the piping system and test medium in an adjacent section, unless two valves are installed in series with a valved “tell tale” located between these valves. A valve shall not be subjected to the test pressure unless it can be determined that the valve, including the valve closing mechanism, is designed to safely withstand the pressure.

4.2.19 Student Book © 2004 Propane Education & Research Council Page 2

Identifying Basic Elements of Pressure Testing

Test Medium. According to NFPA 54, 7.1.2, the test medium shall be air, nitrogen, or carbon dioxide, or an inert gas. Do not use oxygen or fuel gas.

Test Pressure. NFPA 54 requires a test pressure that is 1 ½ times the maximum working pressure for the piping section, but not less than 3 psig.

For example, pipe supplying propane vapor to a second-stage or 2-PSI service regulator may have a working pressure of 10 psig. In this situation, the test pressure is at least 15 psig (1 ½ x 10). However, the second stage pipe supplying propane to the appliances has an operating pressure of 11 inches water column. In this situation, the test pressure is at least 3 psig, and appliances and their controls are not connected to the piping system during the test.

Test Duration NFPA 54 and most state and local codes require a 10 minute test duration for single-family dwellings and small capacity distribution systems with less than 10 cubic feet (1,840 lineal feet of 1” steel pipe). However, if the distribution piping is more than 10 cubic feet, NFPA 54, requires a test duration of 30 minutes for each 500 cubic feet of piping. Regardless of size, NFPA 54 states that the duration of the test need not exceed 24 hours.



Figure 1. Test Gauges InstalledAt Piping Connections at Two

2-PSI Piping Service Entrances

Pressure Measuring Devices. NFPA 54, 7.1.4.1 requires: Test pressure shall be measured with a pressure measuring device designed and calibrated to read, record, or indicate a pressure loss due to leakage during the pressure test period. The source of pressure shall be isolated before the pressure tests are made.

Mechanical gauges used to measure test pressures shall have a range such that the highest end of the scale is not greater than 5 times the test pressure.

For example, a 0-15 psi gauge should be used for a 3 psig pressure test, while a 0-75 psi gauge is required for a 15 psig test.


Procedures Used to Pressure Test Propane Piping

Before testing, check the installation carefully to be sure it is properly installed and meets applicable state and local codes and regulations.

• All pipe, tubing, and fittings used in the installation must meet the requirements in all applicable state and local codes and standards, particularly the National Fuel Gas Code, NFPA 54.

• For new installations, the underground lines and the lines inside buildings must be left uncovered for the duration of the pressure testing.

• All aboveground lines must be properly supported as necessary, and protected from physical damage.

• Before beginning a test, be sure the gauge(s) and test fittings are in good condition. Test fittings equipped with Schrader valves should be fitted with appropriate sealing caps and cap gaskets.



Pressure Testing Integral Two-Stage Distribution Systems: 11 Inches Water Column Operating Pressure— Integral 2-Stage Regulator

Description Test Pressure Minimum Test Duration

Test Medium

PressureMeasuring

Device

Before appliances are

connected

3 psig minimum 10 minutes Air, nitrogen, or carbon dioxide

A pressure gauge designed and

calibrated to read, record, or indicate

a pressure loss due to leakage

during the pressure test period.

Figure 2. Pressure Testing Integral Two-Stage Distribution Lines Operating Pressure: 11 Inches Water Column

This method is intended for testing the main and branch lines before they are connected to the appliance shutoff valves and the integral two-stage regulator. The piping system must withstand a test pressure of at least 3 psig for a minimum of 10 minutes without showing any drop in pressure.



Figure 3. Example of Integral Two-Stage Piping Diagram



Step 1: Make sure the entire line is disconnected from the propane storage container regulator and the ends of all branch lines are either capped or plugged.

Step 2: Install a test adaptor and suitable gauge at any connection in the piping system.

Step 3: Install in the piping system a pressure-measuring device designed and calibrated to read, record, or indicate a pressure loss caused by leakage.

Step 4: Pressurize the piping system to at least 3 psig. A hand pump may be used, as illustrated in Figure 4. The source of pressure shall be isolated before the pressure test is made.



Step 5: Ensure the pressure on the piping system being pressure tested remains constant for a minimum time period of 10 minutes.

Step 6: If the piping system holds the test pressure for a minimum of 10 minutes without any drop, the piping system is considered gastight. (If the piping system is not considered gastight, take appropriate action to locate the leak and make necessary repairs.)

Step 7: Prepare a record that indicates which portions of the piping system were pressure-tested.


Procedures Used to Pressure Test Propane PipingPressure Testing Two-Stage Distribution Systems: 11 Inches Water Column Final Delivery Pressure— 1st & 2nd Stage Regulators


Test Medium

PressureMeasuring

Device

Buried Distribution Line (before regulator

is installed).

Not less than 1.5 (1½) times the maximum working pressure of the first stage line. The typical working pressure of the first stage regulator is 10 psig; therefore, the test pressure should be at least 15 psig.

10 minutes Air, nitrogen, or carbon dioxide A pressure gauge

designed and calibrated to

read, record, or indicate a

pressure loss due to leakage during the pressure test

period.

Second Stage Line, Before

appliances are installed.


Figure 5. Pressure Testing Two Stage Distribution Lines Appliance Operating Pressure: 11" w.c.



Figure 6. Pressure Testing First-Stage Line



Step 1: Disconnect the line from the storage container regulator and the second-stage regulator.

Step 2: Plug or cap the terminating ends of the first-stage line.

Step 3: Install a pressure-measuring device designed and calibrated to read, record, or indicate a pressure loss due to leakage during the pressure test period in the container end of the line.

Figure 7. Installing Test Gauge and Fittings



Step 4: Pressurize the piping system to at least 15 psig. (An air pump may be used, as illustrated in Figure 6.) Then isolate the source of pressure.

Step 5: Ensure the pressure remains constant for a minimum time period of 10 minutes.

Step 6: If the line holds the test pressure without any drop, the line is considered gastight. (If the line is not considered gastight, take appropriate action to locate the leak and make necessary repairs.)



Step 7: Prepare a record indicating the section(s) of pipe tested.

Figure 8. Recording the Pressure Test



Figure 9. Pressure Testing Distribution Lines Downstream of 2nd-Stage Regulator

Service Valve Pipe Cap

Pipe Cap

First Stage Regulator

Pipe Cap

StorageConta iner

Pressure Gauge

Air Check orNeedle Valve

Hand Pum p

Disc o nne c te d2nd Sta g eRe g ula to r

Test the second-stage line(s) by using the same basic method used for integral two-stage systems (a minimum 3-psig test for 10 minutes).



Figure 10.

Furnace

Water Heater

Dryer

2-Pound (Hybrid) Pressure System

Range

M anifoldR

2-psi ServiceRegulator

(2 psig outlet pressure)

Line R egulator

First-Stage Regulator

(10 psig outlet pressure)

Buried PE Tubing

Pressure Testing 2-Pound Distribution Systems: 10 psig buried distribution line pressure and 2-psi delivery pressure to one or more line regulators controlling 11 inches water column final delivery pressure. If the system uses a first-stage and 2-PSI service regulators connected by a buried distribution line, the system is tested as a two-stage piping system (Figure 10).




Test Medium

PressureMeasuring

Device

Buried Distribution Line (before regulator

is installed).

Not less than 1.5 (1½) times the maximum working pressure of the first stage line. The typical working pressure of the first stage regulator is 10 psig; therefore, the test pressure should be at least 15 psig.

10 minutes Air, nitrogen, or carbon dioxide A pressure gauge

designed and calibrated to

read, record, or indicate a

pressure loss due to leakage during the pressure test

period.

Line Connecting 2-PSI Service Regulator to Distribution Manifold.


Distribution Man-fold and

distribution lines to appliances




Figure 12. Pressure Testing First-Stage Line

2 psig CS ST Line toD istribution M anifo ld

F irst-S tageRegulator 2 -P S I S e rv ic e

R e g u la to r

PE First-S tageD istribution L ine

PipeCap

Air Valve-EquippedTest Fitting w ith

0 to 60 psi G auge



Step 1: Disconnect the line from the storage container regulator and the second-stage regulator.

Step 2: Plug or cap the terminating ends of the first-stage line.

Step 3: Install a pressure-measuring device designed and calibrated to read, record, or indicate a pressure loss due to leakage during the pressure test period in the container end of the line.

Step 4: Pressurize the piping system to at least 15 psig. Then isolate the source of pressure.




Step 6: If the line holds the test pressure without any drop, the line is considered gastight. (If the line is not considered gastight, take appropriate action to locate the leak and make necessary repairs. Repeat the pressure test as needed until a gastight condition is maintained.)




Step 1: Remove the line regulator located upstream of the distribution manifold and replace with a pipe nipple. (Figure 13) Verify that all valves at the manifold are manufacturer approved for the pressure that will be used for the test and that the valves are in their open positions.

To test lines in a 2-psi system that uses a single line regulator and distribution manifold:

Figure 13a. Line Regulator and Manifold

Figure 13b. Line Regulator Replaced with Pipe Nipple

for Pressure Test



Step 2: Plug or cap the terminating ends of the lines at appliance locations.

Step 3: Install a pressure-measuring device designed and calibrated to read, record, or indicate a pressure loss due to leakage during the pressure test period in the outside connection where the 2-PSI service regulator is disconnected for the pressure test.

Step 4: Pressurize the piping system to at least 3 psig. Then isolate the source of pressure.




Step 6: If the line holds the test pressure without any drop, the lines and manifold are considered gastight. (If the lines are not considered gastight, take appropriate action to locate the leak and make necessary repairs. Repeat the pressure test as needed until a gastight condition is maintained.)




Figure 14. 2-PSI System with 2 Line Regulators

Furnace

Water Heater

Dryer

CSST Hybrid Dual Pressure System

Range

M anifold

R

2-psi ServiceRegulator

Line Regulator

R

Plastic P ipe in S lab



Figure 15. CSST Multiple Manifold System



Be sure to comply with your company’s pressure testing procedures, along with code requirements of jurisdictional authorities in your area. Also read and follow manufacturer recommendations for pressure testing corrugated stainless steel tubing as appropriate.

4.2.19 Student Book © 2004 Propane Education & Research Council Pages 14 & 15

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

• Complete the Review on page 14.

• See if you are ready for the Certification Exam by checking off the performance criteria on page 15.

4.2.19 student book © 2004 propane education & research councilpage 1 4.2.19 performing...

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