20260910Attachment F - OPS 500.pdf

ATTACHMENT F

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 1 of 14
PURPOSE
To provide procedures for the inspection and maintenance of regulating stations within the MDU Utilities
Group (MDUG) pipeline system.
REFERENCES
External References:
49 CFR§ 192.195- Protection Against Accidental Over-Pressuring
49 CFR§ 192.199- Requirements for Design of Pressure Relief and Limiting Devices
49 CFR§ 192.201 - Required Capacity of Pressure Relieving and Limiting Devices
49 CFR§ 192.605 (b)(5)- Procedural Manual for Operations, Maintenance, and Emergencies
49 CFR§ 192.619- Maximum Allowable Operating Pressure - Steel or Plastic Pipelines
49 CFR§ 192.621 - Maximum Allowable Operating Pressure - High Pressure Distribution Systems
49 CFR§ 192.739- Pressure Limiting and Regulating Stations - Inspection and Testing
49 CFR§ 192.741 - Pressure Limiting and Regulating Stations -Telemetering or Recording
49 CFR§ 192.743- Pressure Limiting and Regulating Stations - Capacity of relief devices
PHMSA Interpretations (PI)92-034 (192.195)and 14-0016 (192.621)
Internal References:
OPS 313—Gas Facility Protection.
OPS 501 — Equipment Calibration, Maintenance, and Testing
OPS 602— Design of Pressure Regulating Systems
OPS 617—Outside Leak Investigation, Pinpointing, and Grading
OPS 703—Valve Inspection and Maintenance
Forms:
N/A
TRAINING AND QUALIFICATION
Technical Training is responsible for the development of training required for MDUG personnel who
perform regulator station inspection and maintenance.
RECORD RETENTION
Record Retention Period Storage Location
Relief Capacity Check Report Five years Electronic copy in Engineering
Services SharePoint site.
Regulator Station Maintenance Five years Compliance tracking software
Form application. (Maximo)
As-Builts and/or modifications Life of pipe Documentum or similar.
Pipeline Inspection Manager,
Pre-June 22, 2020, Legacy Five years Export on SharePoint, and
Maintenance Records Paper Forms in Local District
Offices or Meter Shops.
Pipeline Company(Foreign
Owned) Controlled Regulator Five years SharePoint
Station Inspection
Documentation
DEFINITIONS
Refer to OPS 3 - Master Glossary
I NT-G-26-08
Attachment F
Page 1 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 2 of 14
LOCKUP PRESSURE —The point at which a regulator shuts off completely under no-flow conditions.
OPERATING PRESSURE — REGULATOR—Outlet pressure of regulator under flow. For meter set
outlets, sometimes referred to as Delivery Pressure.
SET PRESSURE— RELIEF VALVE—The pressure at which the relief valve (not the pilot) begins to
operate (e.g., crack, seep, open, etc.).
TOWN BORDER STATION (TBS) -A location at which gas may change ownership from one party to
another(e.g., from a transmission company to a local distribution company), neither of which is the
ultimate consumer. Legacy documents and certain facility names may include industry terms such as city
gate, gate station, or tap (e.g., McCleary Gate Line Heater or Nampa Gate).
SCOPE
Applies to the inspection and maintenance of pressure regulating and relief devices within the MDUG
pipeline system feeding three (3) or more service lines (e.g., GIS Gas Service Point).
PROCEDURE
1. GENERAL
1.1. Periodic inspections and tests shall be performed on regulation stations and relief devices,
including standalone relief devices that are essential and/or non-essential for overpressure
protection.
1.2. Inspection and maintenance shall be documented in the compliance tracking software
applications (e.g., Maximo).
1.3. Descriptions of unacceptable conditions shall be entered in the work order comments.
1.4. Gauges used for inspection and maintenance of regulator stations, relief valves, and
bypassing regulator stations shall be calibrated per the requirements of OPS 501 - Equipment
Calibration, Maintenance, and Testing.
1.5. Regulator Stations are assigned an eight(8) digit unique identification (ID) number. The
unique ID is auto generated by the compliance tracking software application (e.g., Maximo).
The unique ID will be preceded with the Company and Town Code.
1.5.1. Company-Town Code-Unique 8-digit ID.
1.5.1.1. Example: 48425-RS-00012345.
1.6. Pressure limiting stations, relief devices, and the associated equipment shall be inspected at
least once each calendar year, with intervals not exceeding 15 months.
1.6.1. Engineering Services, and System Integrity, shall inform Measurement when
inspection and testing frequencies require increased intervals.
1.6.2. Examples of criteria that may require increased inspection and testing frequencies
due to buildup in regulator or meter components include, but are not limited to,
dithiazine, sulfur, and condensates.
1.6.2.1. Inspections performed outside the frequencies of 1.6 not related to
dithiazine, condensates, or sulfur shall be documented on an AdHoc Work
Order.
1.6.2.1.1. Unless maintenance is required (e.g., rebuilds, pressure
adjustments, etc.)AdHoc Work Orders are not required for
state or federal regulatory agency inspections.
1.6.2.2. If dithiazine, condensates, or sulfur is found during an annual or AdHoc
inspection, a follow-up dithiazine job plan inspection shall be conducted
every three (3) months not to exceed four and a half(4 '/2) months.
1.6.2.2.1. Follow-up inspections shall continue every three (3) months
not to exceed four and a half(4 '/2) months until an inspection
is completed without the presence of dithiazine, condensates,
or sulfur.
INT-G-26-08
Attachment F
Page 2 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 3 of 14
1.7. The lockup and set point pressures for regulators and reliefs shall be determined by
Engineering Services in compliance with §192.201... Required Capacity of Pressure Relieving
and Limiting Devices. The lockup and set point pressure data shall be documented in Maximo.
1.8. The inspections and tests specified in this procedure shall determine that the devices are:
1.8.1. In good mechanical condition and overall appearance.
1.8.2. Set to control or relieve at the correct pressure, consistent with the pressure limits in
Maximo.
1.8.3. Properly installed and protected from insects, dirt, liquids, or other conditions that
might prevent proper operation.
1.9. Exhibit 1 outlines potential inspectable items.
2. START UP
2.1. During the commissioning (e.g., starting up) of new regulator stations, the set pressures of
regulators and relief valves shall be set per the requirements of OPS 602— Design of
Pressure Regulating Systems.
2.2. When a regulator station is utilized to shut in (e.g., isolate) a section of pipeline, the
overpressure protection devices shall be checked for proper operation per the requirements of
this procedure during start up to ensure the maximum allowable operating pressure (MAOP) is
not exceeded.
2.3. When a regulator station is utilized to reduce pipeline pressure during maintenance, the
overpressure protection devices shall be checked for proper operation, per the requirements
of this procedure, when the pressure is returned to normal operating pressure to ensure
MAOP is not exceeded.
2.4. Check for station signage.
2.4.1. If signage is missing and not installed during the commissioning, a Work Order shall
be created in Maximo to have signage installed (e.g., deficiency or AdHoc).
3. GENERAL INSPECTION AND MAINTENANCE
3.1. Prior to performing regulator maintenance, notify Gas Control if the regulator station is
monitored by SCADA.
3.2. The following steps shall be taken prior to regulator inspections and/or maintenance to ensure
safe operating conditions:
3.2.1. Verify in GIS what the station outlet is feeding/serving and if the station is fed from
other regulator stations (e.g., loop fed, back fed, etc.).
3.2.2. Utilize approved gas monitoring equipment while performing regulator station
inspections and/or maintenance.
3.2.3. Utilize two (2) employees while performing maintenance on regulators/reliefs six
inches (6") and larger, unless otherwise approved by management. An example of an
exception is an onsite lifting device/hoist for the removal of heavy regulator and relief
components. Additional employees may be needed when bypassing a station.
3.3. Inspect for leaks.
3.3.1. If qualified, repair the leak.
3.3.2. If not qualified or additional personnel is required, refer to qualified personnel to
grade the leak and schedule repair. Refer to OPS 617 - Outside Leak Investigation,
Pinpointing, and Grading.
3.3.3. Non-hazardous above ground leaks that can be repaired by tightening component(s)
without disassembly and non-hazardous leaks on valves that can be repaired with
grease (e.g., injecting lubricant or sealant)do not need to be reported. Other leak
types require an order to be generated for tracking and permanent record.
3.4. Inspect site conditions.
3.5. Inspect pit or vault condition.
3.6. Inspect soil-to-air interface.
3.7. Inspect for Atmospheric Corrosion.
3.7.1. Pipe in "Poor" condition (e.g., severe corrosion) shall be identified as an AOC.
I NT-G-26-08
Attachment F
Page 3 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 4 of 14
3.8. Inspect pipe supports to ensure all pipe is insulated away from all pipe supports.
3.8.1. If pipe has epoxy coating or other System Integrity approved product at the interface
with the support, the support does not need to be lowered to inspect for corrosion at
the interface.
3.9. For regulator stations enclosed in a building, inspect pipe to ensure it is not in contact with the
building, eliminating risk of electrical shorts, and hazards.
3.10. Inspect barricades, including the condition of existing barricades, or the need to add additional
barricades to protect the facility. Refer to OPS 313—Gas Facility Protection.
3.11. Inspect paint condition.
3.12. Inspect station signage.
3.13. Inspect pipeline markers.
3.13.1. Inspection includes the condition of existing pipeline marker, or the need to add a
pipeline marker(s)at a road crossing, or for better visibility of the regulator station.
3.14. Inspect condition of relief stack.
3.15. Check the position and operation of the relief cap indicator flag, weather cap, or flapper.
3.15.1. Remove weather caps to ensure they are not adhered to the relief stack.
3.15.2. Lubricate or replace inoperable flappers.
3.15.3. Replace missing weather caps.
3.15.4. Replace missing or damaged vent splash guards.
3.16. Inspect and maintain valves that are part of the regulator station per the inspection and
maintenance criteria of OPS 703—Valve Inspection and Maintenance.
3.16.1. Inlet and outlet valves assigned a Maximo ID are included in a separate valve
maintenance program and documented on a Valve Annual Maintenance Work Order
in the compliance tracking software application. Refer to OPS 703—Valve Inspection
and Maintenance.
3.17. Calibrate or check the accuracy of non-transmitting (e.g., no modem) pressure recording
device installed at regulator stations supplied by more than one pressure reducing station.
3.17.1. Pressure recording devices equipped with transmitting devices (e.g., modems) are
included in a separate calibration/maintenance program.
3.17.2. Instruments that are damaged or fail to calibrate will be taken out of service.
3.18. Calibrate or check the accuracy of permanently installed gauges. NOTE: Gauges not used for
accuracy and used as "Indication Only" gauges shall be stickered or labeled as being an
"Indication Only" gauge.
3.18.1. Instruments that are damaged or fail to calibrate will be taken out of service.
3.19. Check pilot heaters for proper operation.
3.19.1. Inoperable pilot heaters shall be repaired or replaced.
3.20. Check inlet pressure with a test gauge rated higher than the MAOP.
3.21. Install a test gauge on the outlet side of the regulator station and monitor the outlet pressure
throughout the regulator and relief valve inspection and maintenance process. Test gauges
shall be rated for pressure that is higher than the MAOP.
4. REGULATOR INSPECTION AND MAINTENANCE
4.1. Regulators shall be set to lockup at the designated lockup pressure, with some allowance for
lockup fluctuation (see chart below), but the regulator shall lockup at a pressure equal to or
less than the MAOP.
I NT-G-26-08
Attachment F
Page 4 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 5 of 14
Lockup Specified Pressure Lockup Fluctuation Allowance +/-
Low Pressure
Up to 14 in/w.c. 1.5 in/w.c.
15-28 in/w.c. 2.0 in/w.c.
Distribution
2-4 psig 0.5 psig
5-10 psig 1.0 psig
11-60 psig 2.0 psig
High Pressure and Transmission
61-125 psig 3.0 psig
126-250 psig 5.0 si
251-500 psig 8.0 si
501+ psig 10.0 psig
*Contact Engineering Services if lockup pressure is left outside the lockup fluctuation
allowance.
4.2. Note: Manufacturers droop capacities are typically for long lengths of pipeline, not the short
spans (e.g., distance between the regulator and outlet valve) used for lockup testing.
4.2.1. When a regulator run is not equipped with the pressure ports required for lockup
testing, the set pressure shall be no greater than MAOP less the manufacturer's
droop capacity.
4.3. Regulator stations that are not equipped with pressure ports to test lockup shall be inspected
per the requirements of Section 1.8.
4.4. Confirm regulator vents are vented down.
4.5. Switching primary (e.g., operating) and secondary(e.g., standby) regulators is allowed but not
required.
4.5.1. When delivery pressure cannot be reduced, the secondary run shall be raised to the
delivery pressure and can be made the primary regulator after maintenance is
complete.
4.5.2. When primary and secondary regulators are switched, the lockup pressure labels
shall be updated.
4.5.3. When the primary and secondary regulator are a different manufacturer or model, do
not switch the runs.
4.6. Switching current secondary regulator to the primary regulator:
4.6.1. Begin by installing the test tree on the secondary run.
4.6.2. Open bleed valve on tree to protect the gauge if regulator fails to lockup. Slowly close
the downstream outlet valve on the secondary regulator run; and watch the
monitoring gauge on the bypass line to verify that there is no reduction in system
pressure. Close the bleed valve on the test tree so the gauge can indicate the lockup
of the regulator.
4.6.3. Note: If the primary regulator does not provide proper pressure or is a single run
regulator station, the station may need to be bypassed during the regulator
maintenance. Refer to Section 7 for bypass procedures.
4.6.4. Turn the adjustment screw on the regulator and bring the secondary pressure up to
the primary lockup pressure as specified in Maximo. Never set a regulator to lockup
above MAOP.
4.6.5. If the regulator fails to lockup, disassemble the regulator and pilot (if applicable),
clean, and/or repair, and retest for lockup.
4.6.6. Fully open the bleed valve on the test tree and verify that the regulator will flow. Then
close the bleed valve to verify that the regulator locks up at the proper set pressure.
4.6.7. If regulator run has a monitor regulator, repeat Steps 4.6.2 through 4.6.6 for monitor
regulator. Set monitor to lockup pressure as specified by Engineering Services. If
I NT-G-26-08
Attachment F
Page 5 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 6 of 14
regulator run is a "working monitor," verify the first stage pilot controls the monitor
regulator at the lockup pressure designated by Engineering Services. Ensure second
stage pilot locks up the monitor regulator at pressure specified by Engineering
Services. Ensure primary worker regulator is aligned and controlling pressure for the
regulating run prior to moving to the next step.
4.6.8. Slowly open the downstream regulator outlet valve, making the secondary regulator
the new primary regulator.
4.7. Switching current primary regulator to secondary regulator:
4.7.1. Install the test tree on the opposite regulator run. This regulator will now be set as the
secondary regulator.
4.7.2. Open the test tree bleed valve to protect the gauge if the regulator does not lockup.
Close the downstream block valve and watch the monitoring gauge on the bypass
line to verify that there is no drop in system pressure. Close the bleed valve on the
test tree so the gauge can indicate the lockup of the regulator.
4.7.3. Open the bleed valve slightly on the test tree to relieve pressure between the
regulator and the downstream valve and turn the adjustment screw on the regulator
to bring the pressure to the secondary pressure setting.
4.7.4. Close the needle valve on the test tree and adjust the regulator to the proper lockup
pressure for the secondary regulator. If the regulator fails to lockup, disassemble the
regulator and pilot (if applicable), clean and/or repair, and retest for lockup.
4.7.5. Fully open the bleed valve on the test tree to verify that the regulator will flow. Then
close the bleed valve to verify that the regulator locks up at the proper set pressure.
4.7.6. If regulator run has a monitor regulator, repeat Steps 4.7.2 through 4.7.5 for monitor
regulator. Set monitor to lockup pressure as specified in Maximo. If regulator run is a
"working monitor," verify first stage pilot controls monitor regulator at lockup pressure,
then ensure second stage pilot locks up monitor regulator. Ensure primary worker
regulator is aligned and controlling pressure for the regulating run prior to moving to
the next step.
4.7.7. Slowly open the downstream block valve and put the secondary regulator into
service.
5. RELIEF VALVE INSPECTION AND MAINTENANCE
5.1. Relief valve capacities shall be reviewed at least once each calendar year, with intervals not
exceeding 15 months, by review of calculations.
5.1.1. Engineering Services is responsible for the review of the relief valve capacities using
calculations.
5.1.2. Engineering Services shall document the annual review of the relief capacity check
on the Engineering Services SharePoint site.
5.1.3. If the capacity of the relief is not sufficient, Engineering Services shall notify the
appropriate department and assist with solution to the relief capacity issue.
5.2. When shutting in relief valves during inspection, testing, or maintenance, the outlet system
pressure shall be monitored to ensure the pressure does not exceed MAOP. If the gauge
monitoring the outlet/delivery pressure cannot be seen while the relief valve is shut in, install a
gauge on the inlet side of the relief block valve or ask for additional personnel to assist with
pressure monitoring.
5.3. Install a test tree with a test gauge on a pressure tap between the relief valve and the relief
isolation valve.
5.4. Slowly close the relief isolation valve to the relief assembly. Constantly monitor the
outlet/delivery pressure for any pressure change.
5.5. Install a high-pressure gas hose rated to the MAOP of the inlet pressure on the test tree to test
the relief.
5.5.1. The hose may be supplied with upstream gas or compressed gas cylinder(e.g.,
nitrogen or compressed natural gas).
INT-G-26-08
Attachment F
Page 6 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 7 of 14
5.5.2. Relief valves shall not be tested by increasing the system pressure through the
regulator station.
5.6. Open the test fitting valve and allow high-pressure gas to open the relief valve. Verify that the
main seat of the relief valve opens.
5.7. Close the test fitting valve.
5.8. Slowly open the valve from the high-pressure hose while watching the test gauge on the test
tree.
5.9. As the pressure slowly increases on the test gauge, the set pressure for the relief valve is the
highest pressure reached until it stops, and main body has cracked open.
5.9.1. Note: The relief valve will be heard when it's cracked open and beginning to vent. At
this point, a pressure drop may be seen on the test gauge once the highest pressure
is achieved, and the relief valve has opened.
5.10. When the set point is found higher than the set point designated in Maximo, adjust the relief
valve to the correct set point.
5.11. Turn off the high-pressure supply and watch the gauge on the test tree to verify that the relief
valve re-seats and does not fall below the upstream regulator's lockup pressure. This is
typically referred to as a relief valve leak test or relief valve re-seat.
5.12. Open the bleed on the test tree to relieve pressure from tree and high-pressure hose.
5.13. Place the relief valve back in service by closing the bleed on the test tree and slowly opening
the relief isolation valve to the fully open position, supplying gas to the relief valve.
5.13.1. With the relief valve in operation, verify the outlet/delivery pressure at the test tree
matches the outlet/delivery pressure at the monitoring point described in Section
3.19.
5.14. Remove the test tree and high-pressure hose and record the station inlet pressure.
6. POST INSPECTION AND MAINTENANCE
6.1. Check that valves are left in the correct position.
6.2. Check that relief valves are locked open.
6.3. Check that bypass valves are locked closed.
6.4. Check that fence gate is locked.
6.5. Install labels (replace old labels if necessary) that identify the regulator pressure setpoints on
the primary and secondary runs and the set pressure on the relief, using stickers or tags (e.g.,
Impresso tags, brass tags, etc.).
6.5.1. Permanently installed analogue gauges shall be labeled "Indication Only."
6.6. Required corrective maintenance (e.g., deficiencies) not repaired at the time of inspection
shall be completed no later than the following time frames:
6.6.1. Inoperable regulators and relief valves shall not be left in service and shall be
repaired or replaced as soon as possible. Regulator stations shall not be left in
service without over pressure protection. When a regulator run or regulator station
must remain out of service due to the unavailability of replacement parts, the
employee performing the inspection or maintenance shall contact their supervisor, or
manager, and Engineering Services.
I NT-G-26-08
Attachment F
Page 7 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 8 of 14
General Inspection and Maintenance Deficiencies Days
Grade 1 Leak Promptly with continuous action
Grade 2 Leak Repaired - No 180
Grade 3 Leak Repaired - No 15 months
Site Condition Unacceptable 180
Vault/Pit Condition Unacceptable 365
Vault/Pit Condition Unacceptable—AOC 10
Soil-to-Air Interface Condition Unacceptable 180
Atmospheric Corrosion Found 180
Pipe Support Unacceptable 180
Paint Condition Unacceptable 1095
Signage Unacceptable 90
Pipeline Markers Unacceptable-Washington 45
Pipeline Markers Unacceptable 365
Relief Vent or Stack Condition Unacceptable 45
Weather Cap Missing/Flapper Not Operable 45
Valve Condition Unacceptable 180
Pressure Recording Device Unacceptable Take out of service or replace
Permanently Mounted Pressure Gauge Unacceptable Take out of service or replace
Pilot Heater Inoperable 45
Regulator and Relief Deficiencies Days
Regulator Vent Not Vented Downward 45
Regulator 1 Lockup Performed Properly—No 45
Regulator 1 Operated Properly—No 45
Regulator 2 Lockup Performed Properly—No 45
Regulator 2 Operated Properly—No 45
Regulator 3 Lockup Performed Properly—No 45
Regulator 3 Operated Properly—No 45
Regulator 4 Lockup Performed Properly—No 45
Regulator 4 Operated Properly—No 45
Relief Operated Properly—No 45
Relief Isolation Valve Locked Open—No 45
Relief 2 Operated Properly—No 45
Relief 2 Isolation Valve Locked Open— No 45
Valves Left in Proper Position— No 45
Regulator 1 Rebuilt-Yes
Regulator 2 Rebuilt—Yes (If YES to all, reset 10-year clock)
Relief Valve Rebuilt-Yes
I NT-G-26-08
Attachment F
Page 8 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 9 of 14
Post Inspection and Maintenance Deficiencies Days
Valves Left in Proper Position—No 1
Relief Isolation Valves Locked Open—No 45
Bypass Valves Locked Closed - No 45
Fence Gate Locked - No 1
7. BYPASSING REGULATOR STATION
7.1. Prior to bypassing a regulator station, notify Gas Control if the regulator station is monitored
by SCADA.
7.2. Unless performed during normal maintenance, bypassing regulator stations shall be done at
the direction of Field Operations Management and/or Engineering Services.
7.2.1. If the above departments are unable to be reached, contact Gas Measurement.
7.3. Contact Engineering Services if assistance is needed with planned bypasses involving
pressure differentials. Bypasses involving the same pressure do not require Engineering
review.
7.4. Bypassing shall be performed with a second employee designated to monitor
downstream/delivery pressure unless the downstream/delivery pressure can be continually
visually monitored while the system is on bypass.
7.5. Prior to bypassing, conduct a job safety assessment, or tailgate, to review the work plan.
7.6. When bypassing a regulator station, the following procedure shall be followed:
7.6.1. Verify relief isolation valve is open and operational.
7.6.2. Monitor the downstream pressure. The gauge shall be installed at a test point where
it can be clearly observed.
7.6.3. When bypassing due to significantly low system pressure, verify that the end of the
system has adequate pressure to maintain service prior to increasing the existing
outlet pressure. Contact Engineering Services if assistance is needed identifying a
significantly low pressure.
7.6.3.1. When SCADA or other monitored pressure device is not available, the
pressure shall be verified with a pressure gauge at the end of the system.
7.6.3.2. Customers in outlying areas of the distribution system may have lost
service. Their service condition will need to be verified and shut off, if
necessary, along with Engineering Services approval before the distribution
pressure could be increased to a normal operating pressure.
7.6.4. When bypassing into a high-pressure system use a gauge that is capable of reading
from zero (0)to the highest pressure possible in the system. The gauge shall be
installed on a test point where it can be clearly observed while operating the bypass
valve.
7.6.5. When bypass runs are equipped with two (2) ball valves (a bypass valve and a
control valve), use the sacrificial bypass valve for bypassing. The upstream valve is
typically designated as the bypass valve and the downstream valve is designated as
the control valve. Always open the control valve prior to bypassing.
7.6.6. Open bypass valve with an adequately sized unidirectional wrench. If the valve does
not turn easily refer to OPS 703—Valve Inspection and Maintenance.
7.6.7. Open the valve gradually to let pressure seep by the valve. During the bypass
process, the pressure on the gauge shall be monitored continuously. Observe the
pressure and control it by throttling. The valve shall not be left unattended during the
bypass operation. The system pressure shall not be allowed to go over system's
designed delivery pressure.
7.6.8. When bypassing is no longer necessary, close the bypass valve and reinstall the
locking device.
I NT-G-26-08
Attachment F
Page 9 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 10 of 14
7.6.9. The system pressure shall be observed to make sure the regulator station is working
correctly and is able to keep up with the current system demand. Monitoring for less
than 30 minutes requires Engineering Services, or System Integrity, authorization.
7.6.10. Remove pressure gauge and confirm the bypass valve is closed and locked off.
8. BLOWING OR RELIEVING (SEEPING) RELIEF VALVE
8.1. First responders that are not operator qualified to perform regulator and relief valve inspection
and maintenance shall notify their Supervisor On-Call as soon as reasonably possible.
Supervisor shall follow local protocol for contacting a Meter Inspector.
8.2. Unqualified personnel shall perform the following steps:
8.2.1. Establish a safety perimeter.
8.2.2. Install gauges on the upstream and downstream of the regulator station.
8.2.3. Relay the upstream and downstream pressures to the Supervisor On-Call, or
Measurement.
8.2.4. Continue to monitor pressure until qualified personnel arrive.
8.2.5. Remain on site to assist until relieved by a qualified individual.
8.3. Qualified personnel shall perform the following steps:
8.3.1. Install a pressure gauge rated for the inlet MAOP on the downstream side of the
bypass valve and read the pressure.
8.3.2. Note the pressures on the regulator labels (the label on the relief valve).
8.3.3. A downstream pressure that is higher than the station's set pressure indicates that
the bypass valve (if present) has been turned to the open position or one of the
regulators has failed.
8.3.4. If the bypass valve has been opened, close it immediately. This shall allow the
pressure to return to normal and the relief valve to stop blowing.
8.3.5. To determine if the problem is caused by a failed regulator, complete the following:
8.3.5.1. Slowly close the inlet valve on the primary regulator and watch the gauge
installed on the downstream side of the bypass valve.
8.3.5.2. If the pressure drops down to normal and the relief valve closes, you have
found the problem. With the inlet valve on the regulator run in the off
position, watch the gauge, and make certain the bypass valve does not
need to be opened to maintain pressure on the system.
8.3.5.3. After closing the inlet valve to the primary regulator, if the pressure on the
gauge remains high and the relief valve still blows, turn the inlet valve back
on, and follow the same procedure on the secondary regulator. If either
regulator does not lockup, it requires immediate repair.
8.3.6. If the gauge pressure is less than the system set pressure, slowly close the relief
isolation valve, and watch the system gauge. If the pressure on the gauge rises to
the relief set point pressure, open the relief isolation valve. This would indicate a
failed regulator or open bypass valve.
8.3.7. If the pressure on the gauge stabilizes to a proper setting after turning off the relief
isolation valve, the relief valve shall be repaired.
8.3.8. Do not leave an inlet or outlet regulator run valve or relief isolation valve in the closed
position without Engineering Services approval. When an inlet or outlet regulator run
valve or relief isolation valve must be left in the closed position, the employee
performing the inspection or maintenance shall contact their supervisor, or manager.
8.3.9. Inlet and outlet regulator run valves and relief isolation valves shall not be operated
unless the outlet/delivery pressure is being monitored.
8.3.10. Remain at the station and monitor pressures until repairs are made and pressures
are normal.
8.3.11. If the problem cannot be resolved after following the above steps, contact a
supervisor, or manager, to request additional assistance.
I NT-G-26-08
Attachment F
Page 10 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 11 of 14
8.3.12. Verify that valves on the station are in their proper position and that the locking
devices are installed and secured on both the bypass valve and the relief isolation
valve.
8.3.13. Inoperable regulators and relief valves shall not be left in service and shall be
repaired or replaced as soon as possible. Regulator stations shall not be left in
service without over pressure protection. When a regulator run or regulator station
must remain out of service due to the unavailability of replacement parts, the
employee performing the inspection or maintenance shall contact their supervisor, or
manager, and Engineering Services.
9. PIPELINE COMPANY (FOREIGN OWNED) CONTROLLED REGULATOR STATIONS
9.1. The following interstate pipeline companies may provide pressure control and over-pressure
protection for MDUG facilities at TBS:
9.1.1. Northwest Pipeline (NWP), a subsidiary of the Williams Companies.
9.1.2. Gas Transmission Northwest (GTN), a subsidiary of TransCanada Corporation.
9.1.3. NorthWestern Corporation, d/b/a NorthWestern Energy (NWE).
9.1.4. WBI Energy, an MDU Resources Group company.
9.2. The pipeline companies are responsible for inspecting these TBS at least once each calendar
year, with intervals not exceeding 15 months.
9.2.1. It is the responsibility of Engineering Services to obtain the inspection documentation
from the pipeline within the required interval. These inspection records shall be
stored on SharePoint.
9.2.2. It is the responsibility of Engineering Services to ensure the regulator and relief set
points are within acceptable ranges.
I NT-G-26-08
Attachment F
Page 11 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 12 of 14
EXHIBIT 1 -
Quality Inspection Protocol Checklist
OPS 500 Related
Section Acceptance Criteria for Conforming Work Quality
Protocol
3.2 a) Prior to performing regulator maintenance, gas detecting equipment is used to QIP 102
check for the presence of natural gas. QIP 103
3 2 2 a) Calibrated gas monitoring equipment is used while performing regulator station QIP 185
inspection.
a) Relief stack flapper is operated to the fully open and closed position OR
lubricated OR replaced if inoperable.
3.14 b) Relief cap indicator flag is operated to the fully open and closed position. QIP 185
c)Weather caps are removed and reinstalled.
d Weather caps and/or vents lash guards are present OR replaced if missing.
Are permanently installed gauges present?
•Yes= inspect, No= proceed to next step
3.16 a) Permanently installed gauges are calibrated OR checked for accuracy. QIP 185
b) Gauges that are damaged or fail to calibrate are removed from service.
c)Gauges not used for accuracy, and used as indication only gauges, are labeled
as"Indication Only."
3.18 c Inlet pressure is checked with a gauge rated higher than MAOP. QIP 185
3.19 d Outlet pressure is checked with a gauge rated higher than MAOP. QIP 185
3.20 a) Pressure gauge is installed on the outlet side of pressure regulation. QIP 102
b Pressure gauge is rated fora pressure higher than MAOP. QIP 103
4.1 a) Regulator is adjusted or verified to operate at a specified set point. QIP 102
c Lock-up pressure does not exceed MAOP.
4.6.5 b) If desired pressures cannot be achieved, regulator is repaired or removed from QIP 102
service.
Was the regulator adjusted?
4.6.5 Yes = Inspect, No = Proceed to next step QIP 102
a After initial adjustment, regulator operation during flow and lockup is reverified.
4.7.7 a Block valves are operated slowly. QIP 102
5.2 b) Station pressure does not exceed MAOP. QIP 102
QIP 103
5.4 a) Station pressure is monitored during the inspection process. QIP 102
QIP 103
a)An MAOP rated high pressure hose is used to supply pressure to the test tree.
5.5 b)Testing pressure is supplied by upstream pressure or compressed gas. QIP 103
c Testing pressure is not supplied by increasing regulator station pressure.
5.9, 5.10 a Relief valve is adjusted or verified tooperate at a specified set point. QIP 103
5.11 c After set point is adjusted or verified, relief valve is leak tested. QIP 103
a) Relief valve isolation valve is operated slowly.
5.13 b) Relief valve isolation valve is closed during testing of the relief valve. QIP 103
c) Relief valve isolation valve is placed in the proper position when maintenance is
complete.
5.13.1 a)With the relief valve in service, test tree outlet pressure matches the station QIP 103
outlet pressure.
6.1 b Block valves are placed in the proper position when maintenance is complete. QIP 102
6.6.1 b) If desired pressures cannot be achieved, relief valve is repaired, or removed, QIP 103
from service.
I NT-G-26-08
Attachment F
Page 12 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 13 of 14
ADMINISTRATION
The Vice President, Engineering &Operations Services of the MDU Utilities Group is responsible for
establishing this policy. Administration of this policy is the responsibility of the Director, Policy&
Procedures.
erluA4NNimK.m Q �.�i��arra
Reviewed: AAN�E��.,,,_�,,,:,��. Approved: ki — GDirector, Policy& Procedures Vice Presldtf,�•`-
Engineering &Operations Services
Date: 8-5-21 Date: 8-5-21
REVISIONS
Major Revision Summary MOC# Date
Original procedure as part of O&M manual integration. Supersedes
CNGC CP 745, IGC 4306 and MDU GDS Sec 9, pg. 134. OPSMOC-359 4/13/2020
Added Section 2. Start Up, Revised Section 3.3.1 (4.3.1 with addition OPSMOC-742
of Section 2)eliminating the need for Measurement personnel to OPSMOC-770 12/15/2020
contact ES. & Removed Section 1.2.1. OPSMOC-791
Removed the rebuild section (previously section 9) and the 10-year
rebuild requirement. Added 6.5.1. regarding "Indication Only"for OPSMOC-1080 6/16/2021
permanently installed analogue gauges.
Updated inspection frequency when dithiazine/sulfur is found in a OPSMOC-884 8/24/2021
regulator.
Minor Revision Summary MOC# Date
Revised 9.2.1. Specifying the storage location of inspection records. NA 7/27/2020
Changed Vault/Pit Condition Deficiency from 45 days to 365 days. 10/12/2021
Added Vault/Pit Condition Deficiency—AOC. OPSMOC-1149
Section 6: Added remediation time frame for grade 2 and 3 leaks in
deficiency table, minor language updates through deficiency table to OPSMOC-1167 2/2/2022
align with other OPS procedures. Update signage from 45 to 90
days.
Revise 4.1. to Regulators shall be set to lockup at the designated
lockup pressure, with some allowance for lockup fluctuation (see OPSMOC-1102 6/8/2023
chart below), but the regulator must lockup at a pressure equal to or
less than the MAOP.
Added 3.7.1. and 7.2.1., Revised 7.6.2. adding language for the OPSMOC-1752 7/19/2023
placement of gauge when a pressure recorder is present.
INT-G-26-08
Attachment F
Page 13 of 14

POLICY STATEMENT OPS 500
Cascade Natural Gas Corporation Regulator Station Inspection and Status: Released
Great Plains Natural Gas Co. Maintenance Revision Date: Oct.28,2024
Intermountain Gas Company OPSMOC-2215&2217
Montana-Dakota Utilities Co. Page 14 of 14
Language has been added to clarify ES completing the annual OPSMOC-1615 & 10/27/2023
reviews of the regulator stations and more clearly document the OPSMOC-1492
reviews.
Add 'condensates' as an item that would require inspection
frequency increase if found to sub-steps of 1.6. Addition of section OPSMOC-1496 & 1/8/2024
2.4. Check for signage. Revised the following sections to state OPSMOC-1920
lockup pressure: 4.5.2., 4.6.7. 4.7.6. Revised section 4.6.4. & 5.9.
Removed section 4.3.1.
2024 Annual Review: Added section 1.9., 3.9., & 3.10. Revised
section 3.8. & pipeline markers unacceptable to 365 days in general OPSMOC-2215 & 10/28/2024
inspection and maintenance deficiencies table. Removed section OPSMOC-2217
4.5.4.
I NT-G-26-08
Attachment F
Page 14 of 14