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Subchapter 1. Unfired Pressure Vessel Safety Orders
Article 6. Anhydrous Ammonia

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§507. Piping, Valves, and Fittings for Liquid and Vapor Lines.

(a) All pipe between the tank and first shutoff valve shall be at least Schedule 80.

All fittings between the tank and the first shutoff valve shall be steel as required by Section 507 (c), first paragraph.

Aboveground piping in excess of 1 1/2-inch pipe size may be Schedule 40 when used beyond the first shutoff valve provided welded, or welded and flanged connections are used.

All other piping shall be Schedule 80.

All piping shall be tested after assembly and proved free of leaks at a pressure of not less than its normal operating pressure or 150 psi, whichever is greater.

Flammable material shall not be used for the installation acceptance pressure test.

All welded piping shall be fabricate and tested in accordance with the ANS Standards Code for Pressure Piping, Section 3, Petroleum Refinery Piping B-31.3, 1966 Edition or equivalent.

All refrigerated piping shall conform to the Refrigeration Piping Code, American National Standards Institute, B-31.5-1966 with addenda B-31.1a-1968 as it applies to ammonia.

Hose shall not be used in lieu of piping between the tank and loading and/or unloading connection, except that a section of metallic hose, not to exceed 24 inches in length may be used in each pipeline to provide flexibility and except as provided in Section 504 (j). The manufacturer's identification required in Section 510 (b) shall be retained on each section.

(b) All piping shall run as directly as practical, with suitable provision for expansion, contraction, jarring, vibrations, and settling. Piping may be either buried or installed aboveground, and shall be well supported and protected against physical damage. All underground piping shall be buried not less than 18 inches below the surface of the ground unless otherwise protected, and shall be adequately coated or otherwise protected against corrosion. Pipe coated as follows will be considered acceptable.

(1) Clean and prime.

(2) Coat with asphalt enamel.

(3) Wrap with forty-pound felt.

(4) Coat with asphalt enamel.

(5) Wrap with forty-pound felt.

(6) Coat with asphalt enamel.

(7) Wrap with Kraft paper.

Equivalent wrapping will be accepted at the discretion of the Division.

(c) All steel fitting used with Schedule 80 pipe shall be Schedule 80 if butt welded, 3,000 pound WOG if socket welded, and 2,000 pound WOG forged steel if threaded.

All other steel fittings shall have a rating of at least Schedule 40 if butt welded and 2,000 pound WOG if socket welded or threaded. Threaded connections shall not be seal welded.

Joint compounds shall be resistant to ammonia.

All other valves and fittings shall be of a type suitable for use with anhydrous ammonia and shall have a pressure rating of at least 400 psi WOG. Valve seat material, packing, gaskets, etc., shall be suitable for anhydrous ammonia service.

(d) The use of the following is prohibited:

(1) Valves, cocks, and pipe fittings of semisteel other than ASTM Specification Nos. A 536-67, Grade 60-40-18; A 395-68; A 445-66; A 47-68, Grade 35018; unless they have a pressure rating of not less than 600 psi WOG. In no case shall valves of semisteel other than thee 4 ASTM Specifications listed above be used for primary stop valves.

Cast iron fittings made specifically for anhydrous ammonia service, meeting ASTM A-126-66 class B or C, may be used for secondary service if they have a service rating of at least 600 psi.

(2) Street ells and screwed service tees unless they are extra-heavy forged construction.

(3) Valves of a design that will allow the valve stem to be removed without removal of the complete valve bonnet, unless the flow is restricted by an inlet orifice to not more than 54 drill gage size.

(4) Ordinary solid-wedge-type gage valves unless there is another stop valve of acceptable type between the gate valve and tank.

(5) Valves with valve stem packing glands which cannot be repacked under pressure, unless there is another valve of acceptable type between it and the tank.

(6) Threaded aluminum fittings and/or adapters that are required to be connected or disconnected as part of the filling or transfer operation.

(7) Copper and brass pipe, fittings, valves, etc.

(8) Pipe, fittings, etc. that are galvanized or otherwise plated with material which is attacked by ammonia where such plating or galvanizing is exposed to ammonia.

(e) Except for service valves, safety relief valves, and gaging connections, all liquid and vapor connections shall have 1 of the following installed directly in the tank connections:

(1) Connections up to and including 4-inch pipe size:

(A) A back-pressure check valve.

(B) An excess-flow valve.

Excess flow valves shall be designed with a bypass, not to exceed a No. 60 drill-size opening to allow equalization of pressures.

All excess flow valves shall be plainly and permanently marked with the name or trademark of the manufacturer, the catalog number, and the rated capacity.

(C) A manually operated check valves (internal valve) equipped with means for closing the valve from a point remote from the delivery connection and with such control mechanism fitted with a fusible section having a melting point of 208 degrees Fahrenheit to 220 degrees Fahrenheit which will cause the valve to close automatically in case of fire.

(D) A positive check valve (internal valve) which can be operated manually and which will close automatically on excess-flow conditions and which can be closed manually from a point remote from the delivery connections. Such valve shall also incorporate a fusible section as required in Section 507 (e) (1) (C) which will cause the valve to close automatically in case of fire.

(E) A positive check valve (internal valve) which is normally closed and which is opened by pump discharge pressure and which can be closed manually from a point remote from the delivery connections. Such valve shall close automatically with a reduction of pump discharge pressure and shall also incorporate a fusible section as required in Section 507 (e) (1) (C) which will cause the valve to close automatically in case of fire.

NOTE: Service valve as used in this order is limited to vapor valves screwed into vessel outlets not larger than 3/4-inch pipe size and having an inlet internal diameter in the valve body not exceeding the internal diameter of a 1/2-inch Schedule 80 pipe.

(2) Valves larger than 4 inch pipe size need not be installed directly in a tank connection, under the following conditions:

(A) The valve must be installed at the first flange or welded joint immediately outside the container in such a manner that any undue strain beyond the valve will not cause breakage between the tank and the valve.

(B) Automatically or remotely controlled valves, or both, of the fail safe type, shall be used. They must also be capable of manual operation.

(C) Piping between the tank and the valve shall be at least Schedule 120.

(D) Acceptance of the valves by the Division must be requested prior to installation.

(E) Where cables are used for remote operation, the control must be fitted with a fusible section having a melting point of 208 Fahrenheit of 220 Fahrenheit, which will cause the valve to close automatically in case of fire.

(f) In addition to the valves required in Section 507 (e), all liquid and vapor connections other than safety relief valve and gaging connections shall be fitted with a manually operated shutoff valve located:

(1) As close to the tank as practicable in all pipelines on connections not included in Section 507 (f) (2) or (3).

(2) In the loading and/or unloading pipelines between the tank and the pump, compressor, meter, or bulkhead, whichever is nearest the tank and in each branch line where it leaves a loading and/or unloading line. This applies only to pipelines on stationary tanks having the loading and/or unloading lines secured to bulkheads specified in Section 501 (e) and having valves complying with Section 507 (e) (1) (D) or (E) installed in the tank connections of such pipelines.

When a pump is attached directly to a valve complying with Section 507 (e) (1) (D) or (E), the manually operated shutoff valve required by this Order may be located between said pump and the meter or bulkhead, whichever is nearest the tank.

(3) In the loading and/or unloading pipelines between the tank and the device used to secure the pipeline as required in Section 504 (i). This applies only to pipelines on transportation tanks having valves complying with Section 507 (e) (1) (D) or (E) installed in tank connections of such pipelines.

507(g)

(g) Every liquid pipeline or hose that can be isolated by 2 or more stop valves shall have a safety relief valve installed in the pipeline or hose to prevent excessive hydrostatic pressure. The safety relief valve required by this subsection shall start to discharge at not less than 300 psi, nor more than 400 psi, and it must relieve to the atmosphere at a safe point of discharge.

(h) All valves, regulators, gaging, and other tank accessory equipment shall be protected against physical damage.

(i) All tank connections requiring manually operated shutoff valves shall be labeled or tagged to indicate whether they communicate with the liquid or vapor space.

(j) The liquid fill line used to transfer anhydrous ammonia from transportation tanks exceeding 3,500 gallons capacity to storage tanks exceeding 2,000 gallons capacity shall be equipped with a backflow check valve to prevent discharge of anhydrous ammonia from the receiving tank in case of hose rupture. This is not intended to prevent transferring anhydrous ammonia from containers, other than transportation tanks exceeding 3,500 gallons capacity, into storage tanks through the load-out line.

(k) All tanks shall be equipped with vapor return valves.

HISTORY:

1. Amendment filed 12-8-72 as procedural and organizational; effective upon filing (Register 72, No. 50).

2. Repealer of subsection (e) and new subsection (e) filed 8-30-74; effective thirtieth day thereafter (Register 74, No. 35).

3. Amendment of subsection (a), (c), (d), (e), (g) and new subsection (k) filed 3-28-75; effective thirtieth day thereafter (Register 75, No. 13).

4. Repealer and new subsections (e) and (f) filed 8-6-76; effective thirtieth day thereafter (Register 76, No. 32).

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