Fuel Gas Piping - Cleaning and Purging

Industry Standards GPTC Z380.1, Z223.1/NFPA 54, & NFPA 56

ASGE 2012 Annual Conference

So Many Standards So Little Time

Topics

Basic Understanding of the Application of

Regulations/Standards
Natural Gas & LP Piping Systems
Choosing the Right Standard

Review Basic Requirements

Cleaning and Purging

General Definitions

Clean No official definition. Remove

debris from a gas conduit.
Purge To free a gas conduit of air or gas,
or a mixture of gas and air. [Z223.1/NFPA
54, 2012]

WHICH STANDARD COVERS WHAT

End use up to 125 psig
ANSI Z223.1 / NFPA 54

Transportation System
Federal Regulations
GPTC Z380.1

Distribution System
Federal Regulations
GPTC Z380.1

End use exceeding 125 psig

NFPA 56(PS)

Transmission & Distribution Systems

Transmission & Distribution Systems

DOT Regulations
CFR 49 Part 192

ANSI GPTC Z380.1

Guidance on DOT Regulations

Purging Principles and Practice

The Technical Basis

Credit information here.

Transmission & Distribution Systems

Part 192 regulations

Provide (mostly) performance
based regulations
Result from Natural Gas
Pipeline Safety Act of 1968
Regulations effective
November 1970
All interstate and most intrastate
operators must comply
Requires operators to develop and
maintain written procedures

Credit information here.

Transmission & Distribution Systems Cleaning

Appendix B to Part 192

Qualification of Pipe.
A. Inspection. The pipe must be clean
enough to permit adequate inspection.
It must be visually inspected to ensure
that it is reasonably round and straight
and that there are no defects which
might impair the strength or tightness
of the pipe.

Requirement
Delivered pipe must be clean
No general cleaning
requirement post construction
in the requirements
Regulations focus on internal
corrosion (steel)

Credit information here.

Transmission & Distribution Systems - Purging

192.629
Purging of pipelines
(a) When a pipeline is being purged of
air by use of gas, the gas must be
released into one end of the line in a
moderately rapid and continuous flow. If
gas cannot be supplied in sufficient
quantity to prevent the formation of a
hazardous mixture of gas and air, a slug
of inert gas must be released into the
line before the gas.
(b) When a pipeline is being purged of
gas by use of air, the air must be
released into one end of the line in a
moderately rapid and continuous flow. If
air cannot be supplied in sufficient
quantity to prevent the formation of a
hazardous mixture of gas and air, a slug
of inert gas must be released into the
line before the air.

Requirement
Purging (in or out of service)
prevent a hazardous mixture of
gas and air.

Credit information here.

Transmission & Distribution Systems - Purging

192.751
Prevention of accidental ignition.
Each operator shall take steps to
minimize the danger of accidental
ignition of gas in any structure or area
where the presence of gas constitutes a
hazard of fire or explosion, including the
following:
(a) When a hazardous amount of gas is
being vented into open air, each
potential source of ignition must be
removed from the area and a fire
extinguisher must be provided.
(b) Gas or electric welding or cutting
may not be performed on pipe or on
pipe components that contain a
combustible mixture of gas and air in
the area of work.
(c) Post warning signs, where
appropriate..

Requirement
Minimize ignition sources
Warn

Credit information here.

10

Transmission & Distribution Systems

ANSI Standard that provides

guidance
Federal 191 & 192 regulations
Published December 1970
Committee consists of gas operators,
regulators, manufacturers and
general interest

Assist operators to meet federal

regulations
Contains gas operator practices
Discussion of issues and
considerations
Appendices covering common
techniques and practices

Credit information here.

11

Transmission & Distribution Systems

GUIDE MATERIAL
192.629 - Purging of
pipelines
1 REFERENCE
AGA XK0101, Purging Principles
and Practice.
2 NOTIFICATIONS
For notification of public officials
and the public in the vicinity of
purge or discharge, see 4 of the
guide material under 192.751.

GUIDANCE
Reference to Purging Principles
and Practice
Contains guidance on
notification

Credit information here.

12

Transmission & Distribution Systems

GUIDE MATERIAL
192.751 - Prevention of accidental ignition.

GUIDE MATERIAL
1 GENERAL
1.1 Smoking and open flames.
1.2 Accidental electric arcing.
1.3 Static electricity on plastic pipe
1.4 Other sources of ignition
1.5 Fire extinguishers
1.6 Verification of the presence of gas
2 WELDING, CUTTING AND OTHER HOT WORK
2.1 General
2.2 Pipelines filled with gas
2.3 Pipelines containing air
3 ISOLATING PIPELINE SEGMENTS ON PLANNED
WORK TO MINIMIZE THE POTENTIAL OF
IGNITION
3.1 General
3.2 Isolating pipeline segments
4 NOTIFICATIONS PRIOR TO PURGE OR
BLOWDOWN
4.1 Public officials
4.2 Public in vicinity of gas discharge
5 REFERENCE

GUIDANCE
Detailed description of
possible ignition sources
Public warning

Credit information here.

13

Transmission & Distribution Systems

Not a standard
Used by gas operators to
assist in the development of
their own purging practices

Credit information here.

14

Natural Gas Systems Above 125 psig

15
Photo courtesy Pacific Corporation

Natural Gas Systems Above 125 psig

NFPA 56(PS) is a Provisional
Standard
Developed under NFPAs
emergency procedures
Response to Kleen Energy
power plant accident
Based on Chemical
Safety Board's
recommendations
Life span of 2 years
Replacement standard
under development

Credit information here.

16

Natural Gas Systems Above 125 psig

NFPA 56(PS) Background

Developed in response to the Kleen Energy
Accident
6 Fatalities, at least 50 workers injured

Photo Courtesy of the US Chemical Safety Board

NFPA 56 PS
CONTENTS
Section 1 Administration
Section 2 Referenced Publications
Section 3 Definitions
Section 4 General Requirements
Section 5 Training Requirements
Section 6 Cleaning
Section 7 Purging into Service
Section 8 Purging Out of Service
Annex A Explanatory Material
Annex B Purge End Points for Common Flammable Gases
Annex C Sample Purge Procedure
Annex D Informational References
18

NFPA 56 PS
SCOPE

This standard shall apply to fire and explosion

prevention during cleaning and purging activities for
new and existing flammable gas piping found in
electric generating plants and in industrial,
institutional, and commercial applications.
Coverage of piping systems shall extend from the
point of delivery to the gas-consuming equipment
isolation valve.
19

NFPA 56 PS
SCOPE
This standard shall not apply to the following items:
Piping systems covered by NFPA 2
Piping systems covered by NFPA 54
Piping systems covered by NFPA 58
LP-Gas (including refrigerated storage) at utility as plants (see NFPA 59)
LNG facilities covered by NFPA 59A
LP-Gas used with oxygen for cutting, welding, or other hot work
Vehicle fuel dispensers
Commissioning and maintenance of appliances or equipment
Vent lines from pressure relief valves
Systems regulated by U.S. Department of Transportation (DOT) 49 CFR
191 and 192
20

NFPA 56 PS
CLEANING AND PURGING PROCEDURES
Written cleaning and purging procedures shall
be developed and implemented
Written procedure for each cleaning and
purging activity shall address, as a minimum, the
following items:
Scope of work and site-specific purge procedure
development
Environmental conditions and work locations
Communication plans
Control of ignition sources
Pre-purge piping system assessment
Purge monitoring and instrumentation
21

NFPA 56 PS
TRAINING REQUIREMENTS

Persons shall be provided with training

Training shall include hazards of flammable and
compressed gases, safe handling practices,
emergency response procedures & equipment, and
company policy
Training shall be conducted by a competent person
and shall be documented
Training records shall be maintained for a period
not less than 5 years
22

NFPA 56 PS
CLEANING OF FLAMMABLE GAS PIPING

Flammable gas shall not be used for internal

cleaning of piping.
Air, inert gas, steam, and water shall be
acceptable cleaning media.

23

NFPA 56 PS
CLEANING OF FLAMMABLE GAS PIPING

Pigs are permitted to be used to clean piping

systems.
Pig cleaning using flammable gas as the propellant
shall utilize a closed piping system.

24

NFPA 56 PS
PURGING INTO SERVICE

Where gas piping containing air is placed in

operation, the air in the piping first shall be displaced
with an inert gas, which then shall be displaced with
flammable gas.
Plants owned or operated by the serving natural
gas supplier in accordance with the serving
suppliers written procedures.

25

NFPA 56 PS
PURGING INTO SERVICE
Discharge of Purged Gases
The vent discharge from a piping system being
purged into service shall discharge directly to a safe
outdoor location as determined by the written purge
procedure

The discharge gases from the permanent piping

system shall be monitored on a continual basis with
appropriate detection equipment
26

NFPA 56 PS
PURGING INTO SERVICE
Discharge of Purged Gas
Purging operations introducing inert gas shall be
continuous until the oxygen concentration detected at
the discharge end is less than 60 percent of the
limiting oxidant
Purging operations that introduce flammable gas
shall be continuous until at least 90 percent
flammable gas by volume or the minimum
concentration established by the purging procedure
27

NFPA 56 PS
PURGING OUT OF SERVICE

Flammable gas piping shall be isolated from gas

supply and downstream piping and equipment
Where existing gas piping is purged out of service,
the residual flammable gas in the piping shall be
displaced with an inert gas.

Plants owned or operated by the serving natural

gas supplier - in accordance with the suppliers
written procedures.
28

NFPA 56 PS
SUMMARY

Prohibits use of flammable gas for internal

cleaning of piping systems
Allows the use of cleaning pigs propelled by
flammable gas in closed systems
Covers activities including cleaning new or
repaired piping systems, placing piping systems into
service, and removing piping systems from service
Requires development of written procedures and a
safety validation of procedures by competent persons

29

Natural Gas Systems Up To125 psi

30
Photo courtesy Palm Beach Plumb

Natural Gas Systems Up To125 psi

National Fuel Gas Code is

the governing standard
Natural gas pressures up
to 125 psig
Gas-air flammable
mixtures up to 10 psig
LP pressures up to 20
psig
NFPA 58 for LP pressures
above 20 psig

Credit information here.

31

Natural Gas Systems Up To125 psi

Same purging
requirements is all
model fuel gas
installation codes

Credit information here.

32

NFGC Cleaning

Pipe shall be cleared

NFGC Purging

Splits requirements
depending on piping size and
operating pressure
Larger Systems are greater
than 2 psig & greater than
certain diameters & lengths

Purging

Purging into or out of

service with inert gas
required for larger systems

Purging

Purging Requirements
Outdoors only
Continuously attend discharge
point
10 ft from ignition sources
10 ft from openings & 25 ft from
mechanical air intakes
Evacuate non-purging personnel
Purging stopped at 90% fuel
gas by volume

Purging

Combustible Gas Indicator

Calibrated
Volume Scale 0%-100% /1%
Increments
Listed CGI

Purging

Smaller systems 2 psi or

less & not meeting the table
pipe diameters and lengths

Purging

Five Methods Provided

Outdoors with no other

requirements
Indoor or Outdoors where
monitored by a CGD
Indoors or Outdoors through
appliance burner
Indoors or Outdoors through a
stand alone burner
Gas supplier written procedures

Purging

Listed & Calibrated

Combustible gas detector is
required
Appliances to be purged prior
to operation

Standards Development Status

NFPA 56 CURRENTLY IN REVISION

Public input and committee actions completed
Draft to be posted by 6/22/12
Public comments are due by 8/31/12
More information at www.nfpa.org

NFPA 54 CURRENTLY IN REVISION

Call for public input due 6/22/12
More information at www.aga.org or www.nfpa.org

Paul Cabot
Administrator National Fuel Gas Code
202.824.7312
pcabot@aga.org
www.aga.org