RELIABILITY PROGRAM

Owner: Inspection Department

Responsibility: Plant Inspectors

Purpose:  To assure the safe and reliable operation of Coke Drums.

Description:

Inspection Intervals:

Inspections will normally be performed in conjunction with Scheduled Unit Slowdowns or Outages.

• API 510 recommends an internal inspection interval not to exceed the lesser of one-half the remaining life to the earliest expected retirement date or 10 years.
• The Inspection Interval will be determined to ensure safety and operability of the equipment.
• Select Circumferential Weld Seams are inspected by UT Shearwave at yearly intervals after the first 3 years of service on new units.
• Drum Skirt attachment welds are visually and NDT inspected at yearly intervals after the first 3 years following new installation.

Coordination:

• Desired Drum Inspections will be determined by the Area Inspector, corresponding with opportune times such as scheduled outages.
• The Area Planner creates necessary Work Orders and Requisitions to support coke drum inspections.
• Inspections will be performed by plant personnel or qualified third-party personnel experienced in pressure vessel inspections and repairs.

External Inspection:

External Inspection should be performed well in advance of the scheduled outage and shall include:

• Condition of stairways, landings, and accessible structural members.
• Skirt condition and de-heading device attachments.
• Historically, cracking at skirt-to-shell attachment welds has been extensive. Inspection of skirts will be performed as allowed by cut cycles. Repairs to skirt attachment welds will be performed incrementally as time allows between cuts; the time between cuts may need to be extended to allow such repairs. Repairs are performed while the vessel is hot to satisfy pre-heat requirements during welding.
• TOFD/UT Shearwave examination of select circumferential weld seams will be performed at yearly intervals after the first 3 years of service on new units.
• Inspection intervals will be adjusted if results of UT surveys and the magnitude of required repairs increase or decrease significantly. Frequencies will be shortened if UT results or Coke Drum performance dictate. The Reliability Department will establish revised adjusted intervals.
• Cumulative crack length relative to vessel circumference will be monitored and considered for repairs if circumferential propagation is suspected.
• The Rotating Equipment Engineer should be consulted for any needed repairs or upgrades to the drill stem rotors.

Internal Inspection:

• Internal Inspection should be performed during Unit Outages unless alternative arrangements are provided.
• Scaffolding will be provided for a visual and dye penetrant examination of the inside weld seams. Indications found will be addressed by blend grinding or repair as required. Areas previously repaired from the outside will be examined from the inside. Any repairs will be ground to a smooth finish.
• Mapping of drum geometry will be performed during Turnaround (T/A) intervals to measure shell bulging, internal liner conditions, and internal weld surface conditions.

Recommendations / Repair:

• Recommendations from External Inspection will be reported and forwarded to the Area Planner for inclusion in the T/A Scope.
• The Area Planner will transmit the Scope to the Repair Organization/Contractor prior to the Turnaround.
• Recommendations from Internal Inspection will be developed by the Area Inspector and forwarded to the T/A Manager as additions to the T/A Scope.
• The Repair Organization/Contractor will perform repairs according to the approved Work Scope, under the supervision of the Maintenance Supervisor.
• An Inspection representative will be assigned to ensure compliance with applicable specifications, document repairs, and make recommendations for successive Turnarounds.

Documentation:

• The Area Maintenance Supervisor closes out all Work Orders through normal T/A or system protocol (e.g., SAP).
• The T/A Report will be developed by the assigned Inspector and stored in the Maintenance Management System (CMMS). Hard copy files will be maintained for documents not compatible with the CMMS.
• Design changes will be documented by the Designer/Engineer, who shall also update the Equipment Data in the designated records vault.