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ENSTAR
Natural Gas Company provides natural gas service through 2,500 miles
of gas mains to over 115,000 customers in South Central Alaska.
ENSTAR’s gas pipeline system is designed, installed, and maintained
with the highest regard for safety in compliance with applicable
federal, state, and local government statutes and regulations. ENSTAR
is regularly inspected to ensure that its operation meets industry
standards.
The US Department
of Transportation Office of Pipeline Safety (DOT) oversees minimum
safety regulations for the transportation of natural gas by pipelines.
The DOT safety regulations are currently published in Title 49 of
the Code of Federal Regulations (CFR).
As an operator
of a natural gas system, ENSTAR is required by the DOT regulations
to:
- Deliver gas safely and reliably to customers.
- Provide training and written instruction for employees.
- Establish written procedures to minimize hazards resulting from
gas pipeline emergencies.
- Keep records of inspections and testing.
- Test employees in safety-sensitive positions for prohibited drugs
and alcohol.
Natural gas is
a potentially dangerous, compressible gas. Gas pipelines with the
highest pressure contain the highest energy storage potential and
present the greatest risk. Caution is always warranted when working
around natural gas facilities. Extreme caution must be exercised
whenever transmission pipelines are encountered. Contact ENSTAR
Engineering Department, (907) 334-7740 for specific instructions
before working within 10 feet of any transmission pipeline.
| Pressure
Classification |
Pressure
Rating Range |
Pipeline
Material |
| Transmission
Pressure |
Greater
than 60 psig |
Steel |
| Distribution
Pressure |
60 psig
or less |
Polyethylene,
Steel, Copper |
- Line
Locating is a Free Service: To request a locate, call Alaska Digline
Inc. in Anchorage @ 278-3121 or statewide @ (800) 478-3121 at least
two but not more than 15 working days before the date scheduled
for beginning the excavation. Hand digging is advised when excavating
within 2 feet of a marked facility. After ENSTAR has field marked
with yellow paint, or flagged the location of an underground facility,
the excavator is responsible for maintaining the markings. Failure
to call is a violation of state statutes and could result in fines
well in excess of the cost of the damage.
- Support for
Steel Line Crossings: If an excavation below a steel gas pipeline
leaves the pipeline unsupported for a distance of more than 20 feet,
the excavator must provide additional support for the pipeline.
Support must be provided in a way as to not damage the pipe or its
coating during construction, backfill placement, and compaction.
Generally, a support spacing of 5 feet or less will provide the
needed bracing. ENSTAR Engineers will provide assistance when required.
Extra care must be taken when geotextile fabric and/or rigid insulation
are used. In addition to continuous support under the pipeline,
compacted fill material shall be placed between the geotextile fabric
and the pipeline. Care shall be taken to insure stability for the
ENSTAR facility. Failure to properly protect ENSTAR’s facilities
could result in future damage if differential settlement occurs.
- Support for
Polyethylene Line Crossings: If an excavation is below a polyethylene
gas pipeline the excavator must continuously support such pipeline
during construction, backfill placement, and compaction. Geotextile
fabric and/or rigid insulation shall be sufficiently separated from
the polyethylene gas pipeline to prevent undue stress during the
compaction/settlement process.
- Support for Steel Line Crossings: ENSTAR
Engineering must approve all excavations crossing steel pipelines
above 4-inch diameter. If support is required, ENSTAR engineering
written approval is required prior to beginning construction. Call
ENSTAR Engineering (907) 334-7740 for further information.
- Excavation Parallel to Pipeline: When
parallel excavations are expected to expose or undermine sections
of pipeline, the excavator must notify ENSTAR engineering in
advance. Care must be taken not to damage the pipeline, or to
induce stresses due to differential settlement following
construction. Long parallel excavations exposing pipelines can be
very dangerous if not properly performed and shall not be
attempted without prior approval by ENSTAR. Contact ENSTAR
Engineering at (907) 334-7740 for additional information.
- Trenchless
Excavation (Vertical or Horizontal): Whenever a trenchless excavation
(horizontal or vertical) is performed within 5 feet of a distribution
pressure pipeline and 10 feet of a transmission pressure pipeline,
the gas pipeline must be exposed to visually determine the exact
location. When performing a trenchless excavation parallel to a
gas pipeline, the gas pipeline must be exposed at intervals of 25
feet or less to visually determine the pipeline’s exact location.
Trenchless excavation is defined as drilling, directional drilling,
boring, pile installation etc.
- Clearance:
Natural Gas pipelines require a 12 inch minimum separation from
other underground structures not associated with ENSTAR’s pipeline
system. Additional clearance from other underground structures may
be required to allow proper maintenance and reduce the possibility
of damage due to the proximity of other structures (49 CFR §
192.325.) ENSTAR requires a 36-inch minimum separation from certain
electrical facilities, including any grounded components i.e. ground
rods, non-insulated conductors and associated structures.
- Pipeline Cover: ENSTAR pipelines in
public rights-of-way are generally installed with 24 inches to 48
inches of cover, and in private rights-of-way with 12 inches to 36
inches of cover. Projects that decrease cover or increase cover in
excess of 60 inches must receive prior approval from ENSTAR
Engineering Department (907) 334-7740. ENSTAR has limited ability
to prevent the removal of cover over gas pipelines. The depth of
cover listed above cannot be assumed after installation. The
excavator is responsible for any damage to ENSTAR pipelines
regardless of the depth at which they are encountered.
- Inspection: All excavations in the
immediate vicinity of ENSTAR Natural Gas facilities (including
backfill, compaction, temporary support, and shoring), is subject
to prior approval and inspection by ENSTAR personnel. Transmission
pipeline inspections are provided whenever an excavator is working
within ten feet of a transmission pipeline. If it has been
determined that there was excavation either by hand or machinery
within 5 ft. of ENSTAR Natural Gas Distribution mains or 10ft.
from ENSTAR Natural Gas Transmission mains without either locates
or standby (qualified ENSTAR personnel), ENSTAR Natural Gas
reserves the right to excavate to determine if there has been any
damage to ENSTAR Natural Gas facilities. If damage has occurred
ENSTAR Natural Gas has the right to charge the excavator for
repairs.
Pipe
Wall Protection
Dents, scrapes, gouges and scratches reduce pipeline wall thickness
and affect the safety of the facility in two ways. First, the reduced
wall thickness decreases the pressure at which the pipeline can
safely operate. Second, the damage serves as a stress concentration
that can cause a future brittle failure of the pipeline. An ENSTAR
representative must inspect each dent, scrape, gouge or scratch,
no matter how small, before it is reburied.
Corrosion
Protection
ENSTAR’s steel pipelines are protected from corrosion by a dielectric
coating and an impressed current or galvanic anode cathodic protection
system. Direct contact with metallic objects (a short) or removal
of the protective coating can compromise this system. Contact the
ENSTAR Engineering Department (907) 334-7740, whenever coating damage
or a short is encountered. An ENSTAR representative must inspect
each short or section of damaged coating before it is reburied.
Locate
Wire Protection
ENSTAR’s polyethylene pipelines are installed with a parallel copper
wire, which is used to locate the pipeline. If the locate wire is
damaged, ENSTAR’s ability to properly locate the pipeline may be
severely compromised. Electrical continuity must be maintained.
An ENSTAR representative must inspect each possible locate wire
damage before it is reburied.
Call ENSTAR any
time a gas line is broken, scraped, pulled, cut or otherwise damaged.
To report a damage, call ENSTAR's 24-hour dispatch number at 1-907-277-5551
or your
local office.
If you smell gas or break a gas line, evacuate the area and eliminate
all ignition sources. Call the Fire Department at 911 if life or property
is jeopardized. Wait for ENSTAR employees to shut off the flow of
gas and make repairs.
Gas lines that have been pulled, stretched, kinked or bent
could be damaged underground away from where the line is contacted. If you
pull or stretch gas lines call ENSTAR at 277-5551 or your
local office and an ENSTAR Representative will investigate for possible
underground leakage.
Only qualified
individuals may perform work on ENSTAR Natural Gas Company facilities.
At a minimum, such individuals must comply with applicable federal,
state and local regulation, statutes, and ordinances.
Page updated:
Tuesday February 28, 2006 |
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