General Service Ball Type Control Valves Technical Specification

1.  Purpose – This article is about Ball Type Control Valves Technical Specification, Related Articles, Codes and Standards, Actuation and Accessories, Ball Type Control Valves Cleaning, Valve Identification, Noise Prediction/attenuation, Ball Type Control Valves Cavitation. This engineering specification defines the minimum design requirements for the supply of ball type control valves in general process plant service.

2. General Service Ball Type Control Valves Technical Specification

2.1       This engineering specification applies to general service ball-type control valves designed for installation in facilities engineered or operated by Company globally.

2.2       All valves supplied under this specification shall be designed for continuous operation, and according to conditions as specified in the accompanying unit specifications.

2.3       Ball valves shall conform to this engineering specification unless the accompanying unit specification indicates otherwise. In case of a conflict, the unit specification shall take precedence.

2.4       This specification does not apply to ultrahigh-purity gas plants or vacuum-jacketed piping systems.

2.5       Valves specified using this specification are required to be suitable for 40,000 on/off cycles per year. Valves are required to operate maintenance free for a four-year duration between normal maintenance outages. A cycle is defined as a valve fully stroked from closed to open and back to the closed position.

3.  Related Articles, Codes and Standards

3.1       Company Engineering Documents

1. Standard Clean (Class SC) Inspection and Acceptance Requirements.
2. Process Clean (Class B) Inspection and Acceptance Requirements.
3. Oxygen Clean (Class AA) Inspection and Acceptance Requirements.
4. Control Valve Actuators and Accessories.

3.2       Fluid Controls Institute (FCI)

FCI 70-2      Control Valve Seat Leakage.

3.3        American National Standards Institute (ANSI)/The International Society for Measurement and Control (ISA)

ANSI/ISA 75.02.01  Control Valve Capacity Test Procedures.

ANSI/ISA 75.08.02  Face-to-Face Dimensions for Flangeless Control Valves ANSI/ISA 75.11.01  Inherent Flow Characteristic and Rangeability of Control Valves ANSI/ISA RP75.23  Considerations for Evaluating Control Valve Cavitation.

3.4       American Petroleum Institute (API)

API 598   Valve Inspection and Testing

3.5       American Society of Mechanical Engineers (ASME)

ASME B16.5       Pipe Flanges And Flanged Fittings NPS 1/2 Through NPS 24

ASME B16.10     Face-to-Face and End-to-End Dimensions of Valves

ASME B16.11     Forged Fittings, Socket-Welding and Threaded

ASME B16.25     Buttwelding Ends

ASME B16.34     Valves – Flanged, Threaded and Welding End

ASME B16.47     Large Diameter Steel Flanges NPS 26 through NPS 60

ASME B31.3       Process Piping

3.6       European Committee for Standardization (CEN)

EN 10204     Metallic products—Types of inspection documents.

3.7       International Electrotechnical Commission (IEC)

IEC 60534-8-1   Laboratory Measurement of Noise Generated by Aerodynamic Flow Through Control Valves.

IEC 60534-8-3   Control Valve Aerodynamic Noise Prediction Method.

DEFINITIONS

Unit specification refers to the document that is written to detail the requirements of a control valve for a specific set of process conditions. This document is transmitted by Company to the supplier for the purchase of the valve and is distributed to design disciplines for information purposes. Separate specifications and documentation used to convey project-specific information are also considered requirements of the unit specification and will be transmitted to the supplier as part of the purchase order documentation.

Ball Type Control Valve refers to rotary, quarter turn ball valves that can be characterized by having a full or partial sphere as the closure member. The sphere (ball) can be full or reduced port with integral devices for control of noise and cavitation. A separate shaft drives the ball by means of a blade or keyed connection to the actuation package.

Cryogenic Extension Valves refer to rotary ball valves designed for cryogenic duty with a single flange connection at the top end of the extension tube. These valves trims are not required to be fully extractable. Maintenance access to the valve’s internals is by removing the valve from the piping system.

5. Ball Type Control Valves Design Requirements

5.1  Valve Body

1. The valve body shall be a rotary, quarter turn ball valve design. The body end connections are permitted to be specified as a flanged, flangeless, weld-end, or screwed end. Valve end connection type will be identified in the unit specification. This specification applies typically to valve sizes DN 20 (3/4 NPS) and larger.
2. Body material will be identified in the unit specification.
3. Valves shall be designed for pressure-temperature ratings corresponding to the ANSI Class ratings as defined in ASME B16.34. When valves are classified by design pressure and temperature rating only, and not ANSI Class, compliance to applicable sections of ASME B16.34 is required. The valve ASME class rating, or design pressure and temperature rating required, will be specified in the unit specification.
4. End-to-end dimensions for flanged, weld-end, and screwed-end ball valves shall be in accordance with ASME B16.10. Face-to-face dimensions for flangeless ball valves shall be supplied in accordance with ANSI/ISA75.08.02. The end-connection type will be specified in the unit specification.
5. Flanged body connections for valve bodies up to and including DN600 (NPS 24) shall be designed to be fitted between flanges in accordance with ASME B16.5. Valve bodies larger than DN600 (NPS 24) shall be designed to be fitted between flanges in accordance with ASME B16.47, Series A. Buttweld end connections shall be in accordance with ASME B16.25. Socket-weld end connections shall be in accordance with ASME B16.11.
6. Valves referenced for purchase under this specification will be components of a process piping system that will be designed and installed in accordance with ASME B 31.3 unless other local codes and standards take precedence. When valves are designated for use in the European Union, it is the suppliers’ responsibility to comply with all EU directives and standards, supplying CE-marked equipment, as required.
7. All pressure-containing parts shall be tested to API 598.
8. Valve bodies for this application are to be classified as fully rated bodies. Fully rated valve bodies are defined as bodies that can withstand a DP equal to its ASME body rating. De-rated valve internals are only acceptable when used in conjunction with fully rated bodies and can only be used by obtaining prior written approval from Company. De-rated valve internals are classified as a valve that has its allowable DP limited to a value less than its fully rated valve body. This can be considered on an application basis where in large size valves this may prove to be an economic alternative.
9. All materials considered as pressure-containing parts are subject to proof of material certification to CEN EN 10204, Type 3.1.B. The supplier shall retain copies of these documents for a ten-year time period for possible review by Company.
10. All valves referenced for purchase under this specification will be new and free of casting defects. New valves are defined as valves manufactured specifically for a purchase order or valves taken from manufacturer or distributor’s stock and not previously used. Damaged or used valves that have been restored to their original condition and carry a new valve warranty are not acceptable.
11. Valve specified for modulating control duty shall have had the flow coefficient (Cv) tested and verified in accordance with ANSI/ISA 75.02.01. Evidence of this testing shall be made available to Company upon request. If such evidence of Cv testing is not available, the supplier shall make available written justification for the offered Cv.

5.2  Ball

1. As a minimum, the ball material will be stainless steel. Alloys or stainless steel balls with hard facing material coatings may be required, depending upon application. Carbon steel balls are not acceptable.
2. Ball valves that offer characterized trims shall have the inherent flow characteristic and rangeability adhere to the requirements of ANSI/ISA 75.11.01.

5.3  Shaft

1. The shaft shall be of a blowout proof design.
2. One- and two-piece shaft designs are acceptable.
3. The manufacturer is responsible for proper sizing and material selection of the shaft to withstand the maximum torque generated by the valve under service conditions.

5.4    Seat Leakage

1. The leakage rate specified in the unit specification is stated as the minimum requirement. Class VI shall be supplied unless a lower level is stated as an absolute requirement in the unit specification.
2. Permitted seat leakage shall be in accordance with FCI 70-2, which defines the levels of leakage from Class I to Class VI.

5.5  Packing and Gaskets

1. All valve packing, gaskets, and O-rings shall be designed to operate at the ASME pressure rating for the valve. Soft goods must also meet the service conditions as stated in the unit specification.
2. The standard stem packing for general service valves is PTFE. Double PTFE v-ring or braided PTFE packing designs are acceptable. Packing type will be designated in the unit specification.
3. Two additional designs of stem packing generally exist for use in valve applications. One design is the standard Grafoil packing, consisting of a series of laminated Grafoil rings. The second design is a live-loaded Grafoil packing that is self-adjusting, and made up of laminated Grafoil rings with a set of spring washers to provide uniform packing pressure. Standard Grafoil packing is preferred in hydrocarbon and toxic service. Live-loaded packing is recommended for use in high- cycle or fugitive-emission service.
4. Asbestos gaskets and packing are not acceptable.
5. Packing gland followers shall be stainless steel, at a minimum.

5.6       Bearings

1. The top and lower bearings, including the thrust bearing (if required), shall be of the manufacturer’s standard design for this application. Material shall be compatible with the intended process conditions as stated in the unit specification.
2. Lubricated bearings are prohibited. All bearings shall be designed to withstand 40,000 cycles per year.

5.7       Installation Orientation

Valves must perform in accordance with this specification and with the orientation of the packing located at any angle at or above horizontal.

6.  COMPATIBILITY AND APPLICATION OF METALS FOR OXYGEN SERVICE

1. The requirement for copper and nickel alloys used in oxygen service will be called out on the unit specification. This requirement applies to all wetted parts in oxygen service.
2. A variety of copper alloys, such as copper, Monel®, tin bronze, red brass, and yellow brass, display exceptionally good oxygen compatibility characteristics. Their use is permitted at all velocities and pressures up to 100 bar g (1450 psig).
3. Nickel alloys such as Inconel® 600 and Inconel® 625 also display good oxygen compatibility characteristics. Inconel 600 to be used up to 69 bar g (1000 psig) with no minimum thickness requirement. Inconel 625 has a minimum 3 mm (1/8 in) thickness requirement and may be up to 86 bar g (1250 psig).
4. The maximum permitted aluminum content for an alloy to be classified as a copper alloy is 2.5%. For the purpose of this specification, aluminum bronze, which typically contains 5 to 13% aluminum, shall be treated as an aluminum alloy and will not be permitted for use in warm oxygen service.

7. ACTUATION AND ACCESSORIES

Actuation and accessory requirements for general service ball valves are addressed in Control Valve Actuators and Accessories and the unit specification.

8. Ball Type Control Valves Cleaning

Cleaning requirements of all process wetted parts to Standard Clean (Class SC) Inspection and Acceptance Requirements, Process Clean (Class B) Inspection and Acceptance Requirements, will be defined in the unit specification. Additional cleaning requirements will be specified in the unit specification.

9. VALVE IDENTIFICATION

1. Each valve shall be supplied with a serial number or other traceable identification marking, which shall be engraved on a stainless steel nameplate. This nameplate shall also include the valve tag number from the unit specification and shall be permanently attached to the valve actuator.
2. Direction of flow arrows shall be permanently attached to the valve body. The valve tag number shall be engraved on a stainless steel tag and permanently attached to the actuator mounting flange.
3. All tags and nameplates shall be stainless steel. Wire tie-wrapped tags are not acceptable. Any additional tagging requirements will be specified within the unit specification or the purchase order document.

10.  NOISE PREDICTION/ATTENUATION

1. Valves shall not be damaged when subjected to the manufacturer’s recommended noise limits.
2. When high noise is likely, the valve manufacturer shall perform a valve noise calculation per IEC-60534-8-3, using the service conditions specified in the unit specification, and advise the specifier if the predicted noise level exceeds valve manufacturer’s limits.
3. Noise calculated using the suppliers’ calculation technique is acceptable. When a discrepancy occurs or the predicted level is debated, the IEC-60534-8-1 method will be used.
4. The unit specification may advise the manufacturer of a lower noise limit that cannot be exceeded. The manufacturer will advise the specifier if the lower noise limit specified is exceeded.
5. The valve manufacturer shall substantiate claims of aerodynamic noise attenuation capabilities in accordance with IEC-60534-8-1.

11.  Ball Type Control Valves Cavitation

1. When cavitation of liquid is likely, the valve manufacturer shall perform a valve calculation verifying the prediction of cavitation using the service conditions in the unit specification. The manufacturer shall advise the specifier if cavitation was predicted.
2. If cavitation is predicted, the manufacturer shall submit recommendations for the specifiers’ review, which will mitigate damage to the control valve and piping system.
3. The valve manufacturer shall be familiar with ISA RP75.23 and its recommendations of successful solutions for cavitation problems.