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Pressure Vessel Alterations and Re-Rating - Coggle Diagram
Pressure Vessel Alterations and Re-Rating
Definition of Alterations
Any change to the vessel design that affects pressure-retaining capacity
.
A physical change in any component that has
design implications affecting the pressure-containing capability of the vessel
.
Fundamentally change the vessel's design parameters or pressure-retaining characteristics.
Unlike routine repairs.
Differentiation from Repairs
Repairs restore a vessel to its original condition without changing its design parameters
.
Alterations
modify the vessel's design or operating limits
.
Examples of alterations include adding or enlarging nozzles, changing wall thickness or materials, and increasing MAWP.
Examples of repairs include replacement of failed welds, addition of welded attachments, and installation of new nozzles that do not affect original strength calculations.
Types of Pressure Vessel Alterations
Physical Modifications
Addition or enlargement of nozzles that affect the vessel's structural integrity
.
Addition of manways or access ports.
Installation of new internal components like cooling baffle plates.
Change in the physical dimensions of a vessel.
Material Changes
Changing wall thickness due to corrosion allowance adjustments.
Upgrading materials of construction for improved performance or longevity
.
Changes to welding materials or procedures that affect pressure retention.
Operational Parameter Changes
Re-rating a vessel for higher temperature or pressure conditions
.
De-rating a vessel based on degraded conditions or changed service requirements.
Re-rating based on new code editions with different material strength requirements.
Modifications to accommodate process changes in a plant.
Requirements for Alterations
Engineering and Design Requirements
Must be
engineered and analyzed according to ASME and API 510
.
All alterations must be engineered and analyzed according to applicable codes.
The "R" Certificate Holder must establish the construction standard and sufficient controls to ensure all required design information is properly managed.
Design Documentation
: Drawings must be prepared with sufficient information to satisfactorily perform the alteration.
Calculations
: Must be completed prior to starting any physical work. Performed by an organization experienced in pressure vessel design and made available for review by the Inspector.
Original Documentation Review
: A copy of the original Manufacturer's Data Report should be obtained where possible.
Welding and Material Requirements
Requires
welding procedures and inspections similar to repairs
.
Materials used must conform to the original code of construction or the selected construction standard.
Companies performing alterations must have a
Certificate of Authorization to use the "R" symbol from the National Board
.
Any weld repairs to ASME pressure zones on tanks require an
R-Stamp certification
.
Inspection and Testing
All alterations must be
inspected and authorized by an Authorized Inspection Agency
.
Testing pressure shall be the minimum required to verify integrity without exceeding 150% of the maximum working pressure.
Non-Destructive Examination (NDE)
must be performed on alterations.
Re-rating calculations must be certified by an engineer
.
Re-Rating Process and Requirements
Re-rating Definition
: Changing its Maximum Allowable Working Pressure (MAWP), operating temperature limits, or both.
Re-Rating Evaluation Process
Initial Assessment
: Review of drawings, client specifications, manufacturing standard code U forms, inspection records, NBIC compliance checklists. Evaluate if re-rating is feasible.
Engineering Analysis
: Engineers model, test, and validate the altered design using software like Compress to calculate new conditions.
Jurisdictional Requirements
: Submitting specific information, including reason for re-rate, original and proposed MAWP and temperature, required physical changes, engineering practices, service history, fabrication drawings, Original Manufacturer's Data Report, and documentation of previous repairs or alterations.
Documentation Requirements
Calculations
: Re-rating calculations must be
certified by an engineer
familiar with pressure vessel design, based on the ASME code.
Inspection Reports
: A detailed inspection report verifying the current condition is required.
New Nameplate
: Upon jurisdictional approval, new nameplates must be created and attached.
Safety Systems
: Description of new safety relieving devices and controls.
Governing Codes and Standards
API 510
: The Pressure Vessel Inspection Code covering in-service inspection, repair, alteration, and rerating activities.
ASME Boiler and Pressure Vessel Code (BPVC)
: Primarily Section VIII Divisions 1 and 2, containing technical requirements for design, welding, NDE, and materials.
National Board Inspection Code (NBIC)
: Especially Part 3, covering Repairs and Alterations.
API 579-1/ASME FFS-1: Used for fitness-for-service evaluations.
Jurisdictional Requirements: Local regulatory bodies may have additional requirements.
Importance
Essential for maintaining safety and compliance when modifying pressure vessels.
Stringent requirements due to safety implications.
Adhering to requirements ensures safe operation and compliance.
Engaging qualified engineers, certified repair organizations, and authorized inspectors is essential.