Management of Change Guide: Replacement of A-Body Valves with Vee-Ball Valves in Hydrofluoric Acid Service
Table of contents
Loading...Fisher Management of Change Guide: Replacement of A-Body Valves with Vee-Ball Valves in Hydrofluoric Acid Service Manuals & Guides
Management of Change Guide
D352048X012 / September 2018
Management of Change Guide for
Replacement of Fisher™ A-Body Valves in
Hydrouoric Acid Service
Table of Contents
Management of Change ..................................2
Background ....................................................2
Question & Answer Checklist ..........................2
Fisher A-body, Masoneilan 10000, and Fisher
Vee-Ball Control Valve Comparison .................5
Face-to-Face Dimensions .................................................... 5
Capacity ............................................................................. 5
Weight ............................................................................... 6
Environmental Compliance ................................................. 6
Suitability for Hydrouoric Acid Service .............................. 6
Conclusion ......................................................9
Additional Resources ......................................9
MOC: Replacing A-Body Valves in Hydrouoric Acid Service
Management of Change
Management of Change (MOC) is a procedure used to proactively manage changes
that have the potential to impact safety or the process within a plant. Evaluating
new techniques for improving MOC approval procedures can have an impact on
plant efciency. Historically, upgrading obsolete products or replacing existing
process control equipment had been delayed or abandoned due to the extensive
paperwork involved in completing a complex MOC approval sheet.
Background
Historically, many Fisher A-body and other double-ported sliding-stem valves have
been used in Hydrouoric Acid Alkylation (HF Alky) units. They were used both
in the UOP and Phillips licenses, but saw more limited usage in UOP’s license due
to the use of a screwed-in seat ring. With UOP taking on full ownership of both
licenses, the A-body construction will see little use in new applications. Although
the A-body has been a successful valve for these acidic applications, it is an
inactive product, which results in challenges in constructing new valves, as well as
maintaining existing constructions.
D352048X012 / September 2018
Emerson has partnered with UOP to determine a suitable replacement for A-body
constructions in HF Alkylation units. This partnership led to the selection of the
Fisher easy-e™ valve (utilizing post-guided trim of the EZ valve) and the Fisher VeeBall™ control valve. The easy-e valve can be used for most applications up to NPS 4.
For valves NPS 6 and larger, it is desirable to use a Vee-Ball control valve solution.
However, shifting from an A-body to a Vee-Ball valve is a signicant change in
control valve selection.
The purpose of this document is to simplify the transition from existing control
valve A-body installations, which may be beyond their service life or no longer
provide the control and reliability required, to the proven reliable Fisher Vee-Ball
control valve.
Contained in this document are two sections. First, there is a question and answer
section to help users complete Management of Change (MOC) approval documents
when modernizing to a Fisher Vee-Ball control valve. Then, there is a side-by-side
comparison of the Fisher A-body, Masoneilan 10000 (also a double-ported slidingstem valve) and the Fisher Vee-Ball control valves. These comparisons demonstrate
how users can safely and efciently replace existing problematic or maintenance-
prone double-ported sliding-stem valves with the Fisher Vee-Ball control valve.
Question & Answer Checklist
Q: Does the proposed modication cause any changes to the piping and
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instrumentation diagram (P&ID)?
A: Possibly. If the valve size changes, concentric reducers to the control
valve inlet and outlet may need to be added to the P&ID.
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MOC: Replacing A-Body Valves in Hydrouoric Acid Service
Q: Does the proposed modication change process chemistry,
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technology, or operating and control philosophies?
A: No.
Q: Does the proposed modication change how the existing plant is
operated?
A: No.
Q: Does the proposed modication change process ows?
A: No.
Q: Does the proposed modication change the process description?
A: No.
D352048X012 / September 2018
Q: Have the codes and standards to which the new equipment was
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designed changed?
A: No, although they may have been updated since the A-body was
installed.
Q: Have the operating and design conditions (ow, temperature,
pressure, process uids) of the proposed modication changed?
A: No.
Q: Does the proposed modication change the materials of construction
such as a change in material form (cast, forged) or alloy?
A: No.
Q: Does the proposed modication introduce new equipment items that
require periodic predictive maintenance?
A: No. The new equipment items will require the same periodic
maintenance as required by the old equipment items.
Q: Does the proposed modication change existing operator training
requirements?
A: Yes. The Emerson sales network offers local training and support to
ensure operators, maintenance personnel, and instrument technicians
are fully trained on the Fisher Vee-Ball control valve.
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