Javier Diaz

Full encirclement split tees along with plugging machines are used to add branch connections to piping in the petroleum industry without shutdowns or process interruptions. The additional branch connections may be necessary to bypass problematic equipment or provide tie-ins for unit modifications. A split tee is an extruded style, carbon steel fitting, fabricated and tested to ASME regulations. ASME regulations require that any branch connections which are inserted in an opening in the run be… Show more

Full encirclement split tees along with plugging machines are used to add branch connections to piping in the petroleum industry without shutdowns or process interruptions. The additional branch connections may be necessary to bypass problematic equipment or provide tie-ins for unit modifications. A split tee is an extruded style, carbon steel fitting, fabricated and tested to ASME regulations. ASME regulations require that any branch connections which are inserted in an opening in the run be attached by full penetration groove welds. To use fillet welds as primary welds, ASME regulations require calculations to be substantiated by testing and simulation. This paper presents the results of tension test, pressure test and metallographic tests performed to cover ASME requirements for the particular case of an actual in-service welded branch connection. Results show what has been proven in the field for years, that the use of fillet welds as primary welds on in-service welded branch connections is a safe practice and technically acceptable, benefiting an industry where process interruptions create considerable losses every year. Show less

This paper summarizes the proposed Redesign and Replacement of the Skirt Attachment of the Coke Drums at the CITGO Corpus Christi Refinery, using an innovative design for existing Drums. Most of the recent advances in the design of this attachment are intended to be installed in new drums. However, this design is specific to existing Drums.
The first cracks in the Coke Drum skirts were found in June 1991. Due to the extensive thermal fatigue cracking, located approximately 1" below the skirt… Show more

This paper summarizes the proposed Redesign and Replacement of the Skirt Attachment of the Coke Drums at the CITGO Corpus Christi Refinery, using an innovative design for existing Drums. Most of the recent advances in the design of this attachment are intended to be installed in new drums. However, this design is specific to existing Drums.
The first cracks in the Coke Drum skirts were found in June 1991. Due to the extensive thermal fatigue cracking, located approximately 1" below the skirt to cone attachment weld, the top 3'-0" of the CCR Drum Skirts were replaced during the March 93 T/A.
At that time, the thermally fatigued sections of the skirt extended from the skirt-to-knuckle weld downward, about six inches.
Frequency and severity of the cracks have increased, even with the 1993 sections replaced, due to the fact that this conventional skirt attachment has been found to crack significantly during the service life of the drum. During the outage of September 2000, inspection revealed a weld cracking of 90% on Drum “A” and 60% on Drum “B”, on the top of the toe of the skirt attachment weld.
There has been extensive research about different types of attachments. A proposal for the redesign and replacement of the skirt attachment on the existing Coke Drums (Vessels 521-V-5A&B), was requested of FW, CB&I, Fluor, Sumitomo and Japan Steel Works. Sumitomo has been chosen as the best option after a detailed evaluation, offering a unique replacement design for existing Drums. Show less

Welding onto an In-Service line is a practice commonly referred to as “Hot Tap welding” and is frequently required for several reasons. In-service welding is potentially hazardous and should only be undertaken when shown to be technically feasible.There are significant economic incentives to perform this welding without removing the system from service and maintain operations. Due to technological advances in In-Service welding, industry needs an update to standards and recommended… Show more

Welding onto an In-Service line is a practice commonly referred to as “Hot Tap welding” and is frequently required for several reasons. In-service welding is potentially hazardous and should only be undertaken when shown to be technically feasible.There are significant economic incentives to perform this welding without removing the system from service and maintain operations. Due to technological advances in In-Service welding, industry needs an update to standards and recommended practices to meet that need.
In 1997, a revision of the current Hot Tap and/or Stopple Procedure was requested, in order to increase the efficiency of proposing, designing and executing Hot Taps and/or Stopples, make it easier to use, present engineering data and calculations for analyzing every case, redefine responsibilities of those involved, incorporate latest developments for in-service welding, provide additional information for special Hot Taps and incorporate checklists for sign-off.
There are a number of difficulties associated with welding onto in-service lines for hot tap connection installation or for maintenance purposes. The approaches used to address these difficulties differ throughout the industry and a number of research projects have been undertaken to address these difficulties.
This presentation documents the upgrading of the Hot Tap and/or Stopple Procedures used at CITGO Corpus Christi Refinery into three separate documents covering an updated Engineering Specification, Drawings and Details and Safety Procedure considering last available technology and recent studies.

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Spring Hangers are designed and engineered to support piping systems and equipment. Either singly or in combination with other standard or special supports, are arranged according to the Hanger Assembly Drawing at each support point. During installation, each assembly must be installed in the location shown on the Hanger Assembly Drawing, within the tolerances listed. Any deviation outside the allowed tolerances shall be justified by engineering calculations.
Each Hanger Assembly is made of… Show more

Spring Hangers are designed and engineered to support piping systems and equipment. Either singly or in combination with other standard or special supports, are arranged according to the Hanger Assembly Drawing at each support point. During installation, each assembly must be installed in the location shown on the Hanger Assembly Drawing, within the tolerances listed. Any deviation outside the allowed tolerances shall be justified by engineering calculations.
Each Hanger Assembly is made of three parts, a structural attachment, a pipe attachment, and an intermediate assembly. Structural attachments shall be welded, clamped, or bolted to structural beams, columns, or embedded plates. Welding of structural attachments shall be in accordance with the requirements of the ASME Boiler & Pressure Vessel Code, Section IX. NDE requirements shall be as shown on the Hanger Assembly Drawing.
The purpose of this paper is to present the Amuay Refinery experience and safe practices in the installation and calibration of new and/or existing Variable and Constant Spring Hangers. The described procedure covers the necessary steps for installation of new Spring Hangers and how to proceed to prior to put them in service, and how to calibrate and maintain existing Spring Hangers. The removal and calibration of existing Spring Hangers should only be addressed during Turnaround. Removal of Spring Hangers during operation should be considered as a particular case and may be acceptable during operation, only when supported by engineering calculations and an approved removal procedure.
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