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Subchapter 14. Petroleum Safety Orders--Drilling and Production
Article 9. Pipe Lines, Fittings, and Valves

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§6533. Pipe Lines, Fittings, and Valves.

a) General.

(1) Pipe lines, piping, fittings, and valves installed prior to July 26, 2006, shall be installed, supported and maintained to withstand the stresses imposed by the internal and external loads, and by contraction, expansion and vibration. This section does not apply to drill pipe, casing or tubing in a well.

(2) The design, fabrication, and assembly of piping systems installed on or after July 26, 2006, and the testing, inspection, and repair of all piping systems shall comply with Title 8, Subchapter 7, Article 146 of the General Industry Safety Orders, and ASME B31.3-2002, Process Piping, ASME B31.4- 2002, Pipeline Transportation Systems for Liquid Hydrocarbons and Other Liquids, ASME B31.8- 2003, Gas Transmission and Distribution Piping Systems, or API 1104, Nineteenth Edition, September 1999, Welding of Pipelines and Related Facilities (including the October 31, 2001 Errata), as applicable, which are hereby incorporated by reference.

(3) Each owner or user of piping shall establish an inspection and maintenance program that will ensure that all piping has sufficient integrity for the intended service.

(A) Each owner or user shall employ appropriate engineering, inspection, classification and recording systems that meet all requirements of this Article.

(b) Inspections.

(1) The inspector shall be an authorized piping inspector as defined in Section 4 of API 570 Piping Inspection Code, Second Edition, October 1998, Addendum 3, August 2003, which is hereby incorporated by reference.

(2) The inspector or piping engineer may employ the principles of API 570-2003 when developing inspection strategies and methodologies.

(3) The piping owner or user shall establish piping inspection risk classes by grouping piping systems into common classes of service, pressure/temperature rating, and risk.

(A) The classification of piping systems shall be determined by a qualified person and shall be based on:

1. The potential for the piping to fail due to corrosion, erosion, and other damage mechanisms;

2. The piping location, history, design basis, operating conditions, and previous inspections; and,

3. The consequences of piping failure relative to its location to employees or the public, potential damage to adjacent equipment, or extent of any environmental impact.

(B) Piping inspection risk classes shall be specified as either Class 1, Class 2, Class 3 or Class 4 as follows:

1. Class 1 piping systems are those that will result in an immediate emergency should a leak occur. Examples include, but are not limited to:

a. Piping systems that contain flammable services that may auto refrigerate;

b. Piping systems that contain hydrogen sulfide greater than 3%;

c. Piping systems that contain highly reactive chemicals such as hydrofluoric acid or anhydrous hydrogen chloride,

d. Piping systems located over or adjacent to public thoroughfares and continuously flowing waterways.

2. Class 2 piping systems are those that contain hydrocarbons that will vaporize slowly during release, strong acids and caustics, hydrogen, fuel gas, or natural gas.

3. Class 3 piping systems are those that contain a flammable liquid that does not significantly vaporize and is potentially harmful to human tissue, but located in remote areas.

4. Class 4 piping systems are those where there is minimal risk based on the likelihood and consequence of failure, such as low pressure water piping, lube oil piping, low pressure piping within secondary containments, or low pressure piping containing a chemical that is not flammable, corrosive, toxic, or reactive.

(4) Inspection intervals and inspection strategy shall be determined by the piping risk classification and the remaining life and corrosion rate calculations. Remaining life and corrosion rate calculations shall be performed in accordance with API 570-2003, Section 7, which is hereby incorporated by reference. When establishing maximum allowable pressure and temperature ratings, the material allowable stress and appropriate non-destructive examination factors from the original code of construction shall be used.

(A) Any signs of leakage or deterioration detected in the interval between inspections shall require inspection of that piping and re-evaluation by the piping inspector, the piping engineer, or a corrosion specialist of the inspection interval for that piping class. This re-evaluation may necessitate a decrease in the inspection interval or an increase in the number of inspection locations. If service conditions change the risk classification, the interval between inspections shall be re-evaluated.

(B) The piping inspection interval for each risk classification shall be established by individuals experienced in piping corrosion and inspection, and shall be set as follows:

1. Class 1 piping systems shall be inspected on a representative sample of piping, as corrosion damage may cause generalized wall thickness loss. The inspection interval shall not exceed 5 years or half the remaining life as determined from the corrosion rate calculation, whichever is less. In cases where the remaining life is estimated to be less than 4 years, the inspection interval may be the full remaining life up to 2 years maximum and the number of piping systems inspected shall be increased within that class to detect worst case deterioration rates.

2. Class 2 piping systems shall be inspected on a representative sample of piping. The inspection interval shall not exceed 10 years or half the remaining life as determined from the corrosion rate calculation, whichever is less.

3. Class 3 piping systems shall be inspected on a representative sample of piping. The inspection interval shall not exceed 15 years or 3/4 of the remaining life as determined from the corrosion rate calculation, whichever is less.

4. Class 4 piping systems shall be inspected and tested in accordance with good engineering practices.

(5) When the inspection of a piping system shows measured losses, the inspector or the piping engineer shall evaluate those losses. This evaluation shall include: establishing maximum allowable working pressure, performing remaining life calculations, retirement thickness determination and assessment of wall losses from general, local and pitting corrosion.

(6) The inspector or the piping engineer shall review all repairs to Class 1 piping systems. Repairs to other piping classes shall be reviewed by the inspector or piping engineer, or the inspector may give prior authorization for specific repair procedures, provided the inspector has reviewed and approved the competency of the repair organization.

(7) Each owner or user shall maintain records of piping inspections. Records shall include classification, inspection type, inspection interval, inspector, inspection results, and corrective actions taken for all piping systems covered.

(c) Pressure relief devices and valves.

(1) Low pressure piping systems connected to a high pressure piping system shall be protected with pressure relief devices that are set to open at a pressure not to exceed the lowest rated working pressure of any component they protect.

(2) Open-ended pipe lines, bleeder lines and flow lines which can be subjected to pressure shall be securely anchored to prevent swinging, revolving, or whipping.

(3) Safe access shall be provided to all valves, or their remote controls, whenever it is necessary to operate them.

(4) Valves or their remote controls shall be provided with a means of ready and safe access when required by the frequency of operation or the necessity of emergency operation. Included in this classification are:

(A) Valves manually operated as often as once a shift.

(B) Valves on fuel lines to a plant, unit, or internal combustion engine.

(C) Line valves.

(5) Manually operated valves required for the emergency shutdown of units shall be maintained in operating condition and provided with ready and safe access. Such valves shall plainly indicate whether they are opened or closed.

(6) Quarter turn valves shall be provided with a means to indicate whether the valve is in the open or closed position.

(7) If a permanently attached handle is used on a quarter turn valve, it shall be installed or placed on the valve in such a position that the handle is at right angles to the line when in the closed position, and parallel with the line when in the open position. If compliance with the provisions of the subsection obstructs a passageway or walkway, the handle may be bent so as to provide clearance.

<General Materials (GM) - References, Annotations, or Tables>

Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.


1. Amendment of subsections (a)-(d), new subsections (e)-(h), and new Notefiled 5-8-95; operative 6-7-95 (Register 95, No. 19).

2. Amendment filed 6-26-2006; operative 7-26-2006 (Register 2006, No. 26).

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