Current through Register 2024 Notice Reg. No. 38, September 20, 2024
(a)
All pressure vessels shall be protected by a pressure relief device. Such
relief devices shall be set to prevent the pressure in the vessel from
exceeding limits established by the ASME Code or, where permitted, the Unfired
Pressure Vessel Safety Orders. Pressure vessels that are connected together in
a system with piping not containing valves that can isolate any pressure vessel
while connected to its source or pressure may be considered as one
unit.
(b) A vessel having a stop
valve that can isolate the vessel from its pressure-relieving device, as
permitted in subsection (c), shall be protected by an additional safety device,
if the vessel may become entirely filled with liquid, and if it is possible
that pressure may be generated by continued input of heat through exchanger
tubes or similar devices or by exposure to sun or adjacent hot equipment. This
additional safety device shall be connected to the vessel at all times except
as permitted in subsection (c)(3). The additional safety device may be set at a
pressure not greater than one and one-quarter times the maximum allowable
working pressure.
(c) Stop Valves
Between Pressure-Relieving Device and Vessel.
(1) A vessel in which pressure can be
generated because of service conditions shall have no stop valve between the
vessel and its pressure-relieving device except for inspection or repair
purposes, as permitted in subsection (c)(3), or except in cases where multiple
pressure-relieving devices are provided and the stop valves are so constructed
that they can not be operated so as to reduce the pressure-relieving capacity
below that required.
(2) A vessel
in which the pressure originates from an outside source exclusively may have
its pressure-relieving device on the vessel or at any point on the system
between the vessel and its source of pressure, provided that the
pressure-relieving device is set to function at not over the maximum allowable
working pressure of the vessel. Under these conditions there may be a stop
valve between the vessel and the pressure-relieving device which need not be
locked open if the stop valve also closes the vessel from its source of
pressure. Any stop valve between the pressure-relieving device and the vessel
which does not close the vessel from its source of pressure shall meet the
requirements given in subsection (c)(1) above.
(3) Stop valves may be installed between a
pressure relief device and the operating vessel for the purposes of inspection,
repair and/or replacement of the pressure relief device. Where stop valves are
installed, the employer shall develop, implement, and maintain a written plan
containing all of the following:
(A)
Procedures to ensure that stop valves are open and locked or sealed during
normal operations and are not to be closed except by a qualified person(s).
NOTE: In the case of multiple relief device installations
having spare capacity or spare relief valves, the stop valve can be closed on
the inactive relief valves providing sufficient system relief capacity is
maintained.
(B) Procedures
to minimize the frequency of closing stop valves while the vessel is in
service. Stop valves shall remain open and locked or sealed until a replacement
pressure relief device is available for installation.
EXCEPTION: Stop valves may be closed for emergencies such
as pressure relief device failure.
(C) Procedures to ensure that a replacement
pressure relieving device or needed replacement parts are readily available
prior to closing the stop valve and removing the pressure relief device. An
index for the location of all stop valves subject to this section shall be
maintained.
(D) Before the removal
of a pressure relief device from operating equipment, facility management shall
review and approve a written operations plan for closing the stop valves. The
plan shall incorporate, at a minimum, the following elements:
1. An engineering review to ensure that no
increase in the capacity, pressure, severity, and/or operating condition of the
unit or vessel will affect the safety of employees or equipment while the
pressure relief device is out of service.
2. Provisions for written notification and
operational procedures to unit controllers, operators and other affected
personnel, including the safeguards and estimated time the valve will be out of
service.
3. Identification of the
functional position(s) or employees having knowledge of the operating equipment
and pressure relieving device(s) authorized to approve closing a stop valve;
and,
4. Identification of the
qualified person(s) or functional position(s) authorized to actually close and
then reopen a stop valve.
(E) A written overpressure relief plan for
each safety relief device shall be developed prior to closing the stop valve.
The plan shall include:
1. The means by which
overpressure-relief protection will be provided during the time that the
pressure relief device is out of service;
2. The procedures to be followed to minimize
the time that the stop valve will be closed;
3. The operating conditions, limitations, and
other safety measures which are required to be observed to protect employees
and equipment; and,
4. In the event
that the plan requires a standby person to manually operate a vent to the
atmosphere, a replacement safety relief valve shall be available for
installation prior to closing the valve. Employees shall be protected from
hazards as identified by Article 10 of the General Industry Safety
Orders.
(F) The written
overpressure-relief plan shall be made available to the Division upon request
during the course of the work operation to which it
applies.
(4) Valves as
permitted above shall not be gate valves installed with the stems pointing
above the horizontal plane of the valve body or globe valves installed so that
the disk will open against pressure. This limitation need not apply to stop
valves closing the vessel from its source of pressure. Other provisions
acceptable to the Division may be used to assure that the valve is in the open
position.
(d) Capacity of
Pressure-Relieving Devices.
(1) The aggregate
capacity of the pressure relief devices applied to any pressure vessel or
system shall be sufficient to carry off the maximum quantity of material that
can be generated in, or supplied to, the attached equipment without permitting
a rise in pressure within the vessel above the limits permitted by the ASME
Code.
(2) Pressure relief devices
designed to relieve hydrostatic pressure caused by heat as outlined under
subsection (b) shall have sufficient relieving capacity to prevent a
hydrostatic pressure within the vessel in excess of 1.33 times the maximum
allowable working pressure.
(e) Discharge lines from pressure relief
devices shall be secured against movement. The lines shall be designed to
facilitate drainage or shall be fitted with drains to prevent liquid entrapment
in the discharge side of the relief device. The lines shall discharge at a
location or in a manner to prevent injury to employees. The size of the
discharge lines shall be such that any pressure that may exist or develop will
not reduce the relieving capacity of the relief device below that required to
properly protect the vessel. No valve shall be placed in a discharge line from
a pressure relief device except when such discharge line discharges to a common
header, in which case such valve shall be installed in compliance with
subsection (c)(4) and locked or sealed open. Such valves may be closed only as
allowed by subsection (c)(3).
(f)
The employer shall maintain each pressure relief device installed on operating
equipment so as to ensure the proper functioning of the device at the intended
pressure. Such maintenance shall include inspection, testing, and the repair of
the pressure relief device at frequencies as required by the service
conditions.
(g) Pressure relief
valve settings shall be changed only by authorized employees assigned such
duties.
(h) A permanent and
progressive record for each pressure vessel shall be maintained at the plant or
the field office where the vessel is located. The record shall be available for
inspection by the Division and shall include the following:
(1) The serial or identification number of
the vessel.
(2) The established
maximum allowable working pressure of the vessel.
(3) The coincident design
temperature(s),
(4) Manufacturer's
data reports, when obtainable, and any calculations used in establishing the
maximum allowable working pressure.
(5) Such documents as necessary to record the
results of tests, inspections, repairs, or alterations. Information on
maintenance activities and events affecting the pressure vessel's integrity
shall be included.
(i)
Each pressure relief device in service shall have a serial or identification
number stamped upon it and, in addition, a metal plate or tag shall be attached
showing the pressure setting and the date the device was installed in service.
A permanent and progressive record showing the serial or identification number,
the location, the pressure setting, the date of installation in service, and
the date of testing shall be maintained at the plant or field office where the
pressure relieving device is located or at the supervising office.
1.
Repealer and new NOTE filed 5-8-95; operative 6-7-95 (Register 95, No.
19).
2. Amendment of section heading and new section filed
6-26-2006; operative 7-26-2006 (Register 2006, No.
26).
Note: Authority cited: Section
142.3, Labor
Code. Reference: Section
142.3, Labor
Code.
