2005 API NPRA Ops Sym E1308 Bundle Launch

Inadvertent Exchanger Tube

Bundle Extraction a Safety Critical Mistake

James R. “Chezo” Cesarini, PE

Maintenance Manager

Valero Refining - Texas, LP

Texas City, Texas

[email protected]

Inadvertent Exchanger Tube Bundle Extraction … a Safety Critical MistakeInadvertent Exchanger Tube Bundle Extraction … a Safety Critical MistakeInadvertent Exchanger Tube Bundle Extraction … a Safety Critical Mistake

Operational Situation

• September 30, 2005 @ 06:30 AM

• Shift Change @ Gas Oil

Hydrotreater (GOHT) Unit

• Cold Separator Trim Condenser

– E-13-1308

• Plant down from hurricane Rita – in

process of starting up

• Tube leak identified during start up

requiring bundle replacement

• Having difficulty extracting bundle

from shell - 50K LB with extractor

• In addition to bundle extractor,

have added 450 LB steam in the

shell – common practice

• Currently in process of adding

stress relieving coils to shell – also

common practice

• 8 ½ hours of steam addition

• Adding additional coils to

expand shell

• Rapid heat ramp to 800 Deg. F.

• Steam escaping from bottom

shell nozzle– Cooling Water Inlet

• Blind on CW Inlet was tightened

to lessen steam loss

• Pressure built in the shell (> 360

psig)

• Shell condensate quickly

became steam

• Steam exit orifice equal or

smaller than entrance orifice


Incident Description

• Closing the bottom blind (CW

Inlet – 450 LB Steam Inlet)

allowed the following to occur:

– Pressure to build In the shell

– Rapid vaporization of

condensate to steam

(reaching sonic velocity)

– expansion of shell (coupled

with the external heating coils)

• Result

– One Inadvertent Bundle

Launch

• Bundle contacted extractor gear

box and landed 58 feet away

• Extractor gear box traveled 108

feet through sour water pumps


Incident Description


Root Cause of Incident • Impatience - extended length of

time to extract bundle

• Loss of focus – Deviation of

proven procedure without

thorough review

• Pressure build in shell due to

inadequate venting

• Volumetric expansion of

condensate to steam

• Excessive heat ramp with

external coils (rapid shell

expansion)

• Steam alignment incorrect from

the beginning entering from the

bottom and exiting from the top

• EIL source violation – adding an

energy source to LO/TO item

Steam added from the bottom

+ Blind Flange was later closed

Reduced area of escape for steam + Condensate build in vessel–no escape

Additional Heat

Source - 800 Deg. F.

• More rigorous procedure to

extract bundle is necessary

• Increased communications

necessary when making a

change during a process

• Avoid using a compressible

fluid in all cases if possible

• Adding steam to LO/TO item is

breech of the Energy Isolation

List (EIL)

• Add a pressure indicator to the

system for safety observation

• Additional craft training and

observation regarding steam

line up is warranted

• Have an experienced technician

or engineer review/calculate the

configuration


Lessons Learned

• Providing additional LO/TO and

EIL training to all refinery

personnel

• Informing all within Valero

Refining system about incident

• Informing petrochemical

community about incident

• Preparing procedure to safely

extract difficult bundles

• Amending refinery Safety and

Health Guideline for LO/TO and

EIL

• Requiring a pressure indicator

with this configuration


Counter Measures

• Bundle change provided

opportunity to install new

proprietary patented pressure

seal

• Pressure seal allowed

exchanger reassembly without

welding on another diaphragm

• Successful pressure seal

installation paved the way for

future modification on 13 other

exchangers

• Successful pressure seal will

save substantial $$$ for all

future shutdowns

– Time savings

– Easy assembly

– Reliability issue resolved


Opportunity Provided (!) – Existing Arrangement

• Leak Free Service

• Interest has exploded

– VLO McKee

– VLO Delaware City

– VLO Wilmington

– Eastman TN

– VLO Texas City

• Everyone likes their

own idea!


Opportunity Provided (!) – Post Modification

• Incident

• EIL violation – adding energy

source to a LO/TO item

• Inadequate venting of steam

during use as a heat source

• Loss of concentration during

heat of battle

• Opportunity

• Opportunities exist even during bad

situations

• Thinking outside the box today will

save $MM for us going forward

• Thinking outside the box can still

be considered coloring within the

lines


Summary

Documents

2005 API NPRA Ops Sym E1308 Bundle Launch