Relining of post weld heat treated vessel.

Mechanical / Civil engineering, Design of Pressure Vessels, Heat-exchangers, Piping, Steel / Civil Structure etc.

Relining of post weld heat treated vessel.

Postby tayyabeme » 23 Jun 2014, 06:39

Is partial relining of post weld heat treated vessel allowed. The vessel operates at 30Kg/cm2 180C with a service (60 Mol% hydrogen)

Please share similar experience..
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Re: Relining of post weld heat treated vessel.

Postby kune » 24 Jun 2014, 06:15

Would you please share some more details about the pressure vessel?
What's the base material? Lining material? PWHT, a service requirement or based upon material chemistry? Design code of vessel?
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Re: Relining of post weld heat treated vessel.

Postby tayyabeme » 01 Jul 2014, 08:17

Vessel is condensate seperator in syn gas service.
Material of construction is A212 BFB.
Thickness of shell and head is 40mm.
Design code is ASME Sec VIII, 1962 edition.
And the vessel is post weld heat treated.
Lining material is SS 304L 3mm thk.

I have been considering this case myself as well. As per my working ASME Sec VIII Div.1, UCL 34 gives guidelines for PWHT of vessels with lining.

Please tell me about your interpretation for the clause:

"Vessels or parts of vessels constructed of chromium stainless steel integral or weld orverlay cladding and those lined with chromium stainless stell applied linings shall be postweld heat treated in all thicknesses."

Does this clause employ that all vessels with SS lining will be post weld heat treated regardless of the provision in UCS-56 note for P No. 1 G No.1 stating that, PWHT is not mandatory "for welds attaching resistant lining (see UCL-34) provided preheat to a minimum temp. of 95C is maintained during application of first layer when thk. exceeds 32mm).

Please comment.....
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Re: Relining of post weld heat treated vessel.

Postby tayyabeme » 01 Jul 2014, 13:32

Vessel Descirption: Condensate Knockout Seperator
Service: Syn Gas
Material of Construction: A212 BFB
Shell and Head thickness: 40mm
Liner Material: SS-304L
Liner thickness: 3mm
Vessel post weld heat treated. The vessel is already lined and we want to replace the lining.

I have been looking into this case myself as well. Following are my findings:

UCL 34 addresses this case. It states:

"Vessels or parts of vessels constructed of applied corrosion resistant lining material shall be postweld heat treated when the base material is required to be postweld heat treated."

(In our case the vessel is already heat treated.)

"Vessels or parts of vessels, those lined with chromium stainless steel applied linings shall be postweld heat treated in all thicknesses."

Moreover UCS-56 for P # 1 and Group # 1 states PWHT is not manadatory :

"for welds attaching corrosion resistant lining provided preheat to a minimum temperature of 200F is maintained during application of the first layer when the thickness of the pressure part exceed 1.25"."

DOES UCL-34 IMPLY THAT ALL WELDS FOR ATTACHING CHROMIUM SS LINING WILL BE HEAT TREATED REGARDLESS OF THE FACT THAT THE VESSEL WELDS ARE ALREADY HEAT TREATED?

HOW DO WE INTERPRET UCS-56 IN LIGHT OF UCL-34
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Re: Relining of post weld heat treated vessel.

Postby ben » 01 Jul 2014, 17:08

The principal code to follow for this job is API 510.
At the moment, I have 2003 edition of API 510. Below is the applicable paragraph:

7.2.6 Repairs to Stainless Steel Weld Overlay and
Cladding
The repair procedure(s) to restore removed, corroded, or
missing clad or overlay areas shall be reviewed and endorsed
prior to implementation by the pressure vessel engineer and
authorized by the inspector.
Consideration shall be given to factors which may augment
the repair sequence such as stress level, P number of base
material, service environment, possible previously dissolved
hydrogen, type of lining, deterioration of base metal properties
(by temper embrittlement of chromium-molybdenum
alloys), minimum pressurization temperatures, and a need for
future periodic examination.
For equipment which is in hydrogen service at an elevated
temperature or which has exposed base metal areas open to
corrosion which could result in a significant atomic hydrogen
migration in the base metal, the repair must additionally be
considered by the pressure vessel engineer for factors affecting
the following:
a. Outgassing base metal.
b. Hardening of base metal due to welding, grinding, or arc
gouging.
c. Preheat and interpass temperature control.
d. Postweld heat treatment to reduce hardness and restore
mechanical properties.
Repairs shall be monitored by an inspector to assure compliance
to repair requirements. After cooling to ambient temperatures,
the repair shall be inspected by the liquid penetrant
method, according to ASME Code, Section VIII, Division 1,
Appendix 8.
For vessels constructed with P-3, P-4, or P-5 base materials,
the base metal in the area of repair should be examined
for cracking by the ultrasonic examination in accordance with
ASME Code, Section V, Article 5, paragraph T-543. This
inspection is most appropriately accomplished following a
delay of at least 24 hours after completed repairs for equipment
in hydrogen service and for chromium-molybdenum
alloys that could be affected by delayed cracking.


With syn gas means that hydrogen there? Right?
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Re: Relining of post weld heat treated vessel.

Postby kune » 02 Jul 2014, 12:21

Your interpretation of no mandatory PWHT required as per UCS-56 is right. Yes, there is no need to perform PWHT if preheat temperature is maintained at 200 F at minimum.
UCL-34 (b) doesn't apply in your case as you have chromium-nickel stainless steel lining that is 304L.

Hope this helps.

tayyabeme wrote:Vessel Descirption: Condensate Knockout Seperator
Service: Syn Gas
Material of Construction: A212 BFB
Shell and Head thickness: 40mm
Liner Material: SS-304L
Liner thickness: 3mm
Vessel post weld heat treated. The vessel is already lined and we want to replace the lining.

I have been looking into this case myself as well. Following are my findings:

UCL 34 addresses this case. It states:

"Vessels or parts of vessels constructed of applied corrosion resistant lining material shall be postweld heat treated when the base material is required to be postweld heat treated."

(In our case the vessel is already heat treated.)

"Vessels or parts of vessels, those lined with chromium stainless steel applied linings shall be postweld heat treated in all thicknesses."

Moreover UCS-56 for P # 1 and Group # 1 states PWHT is not manadatory :

"for welds attaching corrosion resistant lining provided preheat to a minimum temperature of 200F is maintained during application of the first layer when the thickness of the pressure part exceed 1.25"."

DOES UCL-34 IMPLY THAT ALL WELDS FOR ATTACHING CHROMIUM SS LINING WILL BE HEAT TREATED REGARDLESS OF THE FACT THAT THE VESSEL WELDS ARE ALREADY HEAT TREATED?

HOW DO WE INTERPRET UCS-56 IN LIGHT OF UCL-34
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Re: Relining of post weld heat treated vessel.

Postby tayyabeme » 05 Jul 2014, 11:02

Dear Ben: Synthesis gas is almost 50% hydrogen and 50% nitrogen used for formation of ammonia.

I took opinion from some others as well. They are as follows:
Thangavelu
Thangavelu Kumaresan
TA Inspection Consultant at Binh Son Refining and Petrochemical Co., Ltd

Hi Muhammad,
For your case PWHT is not required, since your base material already PWHT had been
done, and you can use pre-heating method instead of PWHT after that do NDT Inspection.

Table UCS 56 Notes (2)(c)(5) clearly say's that PWHT not required provided pre-heating temperature min of 950C is maintained during first layer when the base metal thickess exceeds 32mm thickness, but this applicable for new construction only.

For your case, I blieve your vessel has been in service for some time, now it is required lining repair / replacement, so this repair method shall follow as per the API 510 repair guide line ( class 8.1.5.4).

For your case, repair procedure shall be developed by a competent person, there are so many factors(what service was used, and as per that outgassing required or not ,hardening & pre heating temp) that need to be considered when repair procedure is developed by a competent person.

Regards
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MAHENDRA KUMAR RASTOGI
MAHENDRA KUMAR
MAHENDRA KUMAR RASTOGI
VICE PRESIDENT - INSPECTION & RELIABILITY at Bharat Oman Refineries Limited

You do not require any PWHT after new SS 304 lining over already in service CS vessel.

regards,
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Muhammad Tayyab Siddique
Muhammad Tayyab Siddique
Project Engineer at Fauji Fertilizer Bin Qaism Limited
Top Contributor

Dear Mr. Kumaresan

You are absolutely right, the vessel has been in service for almost 30 years. Decision for liner replacement has been taken due to cracks observed in circumferential seams of liner. Even after repair, leakage still persists. Despite leakage, the vessel is currently in service.
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Suresh
Suresh Dudala
ASME AI / AIS / ANI at TUV Thuringen

Hi Muhammad,

Pls. be clarified that the following comment in your query does not apply to corrosion resistant liner materials made of 304 / 304L ( 3XX series ).

"Vessels or parts of vessels, those lined with chromium stainless steel applied linings shall be post weld heat treated in all thickness's."

Chromium stainless steels are 4XX series which need PWHT when welded in all thickness.

It would be a very rare design at present for a vessel made of liners for corrosion / erosion resistance as a service condition ( except for nozzle sleeves ). Clad plates are the replacement for liner design for the vessel shell / heads.

During welding of liners, dilution with the substrate ( Base metal ) is to be taken into consideration in case the weld joint is resulted in between liner and BM.
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Laudelina Casado
Laudelina
Laudelina Casado
Mechanic Consultant for Chemical and Petrochemical Plants
Top Contributor

Muhammad

You said "Even after repair, leakage still persists. Despite leakage, the vessel is currently in service". It means that your cracks are through the vessel wall. Did you conduct a Fitness for Service, API 579 in order to know if you can run the vessel in this condition? , and prepare a better repair or vessel replacement. API 510 or ASME PCC-2 repair codes.
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Muhammad Tayyab Siddique
Muhammad Tayyab Siddique
Project Engineer at Fauji Fertilizer Bin Qaism Limited
Top Contributor

Dear Miss Casado

Probing operation history of this vessel reveals that:

Pinholes have been observed in early turnaround which have been repaired through buildup.Cracks on liner to shell welds have been observed frequently as well.

In last turnaround vessel inspection was carried out. Moreover SFT of the liner was also carried out through weep holes at 6Kg/cm2. 7 cracks were found in manway lining. 2 pinholes on welds between lining, and 5 pinholes were observed in liner.

All of the above observations were repaired and the vessel was proceeded for box-up. However upon plant startup minor explosivity was observed through weepholes. The vessel is under observation, while being in service.

Till now fitness for service has not been carried out.
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Arjun Prasad, P.E.
Arjun
Arjun Prasad, P.E.
Consulting Engineer at URS
Top Contributor

There are two repair Codes for pressure vessels. Besides API-510 (normally for petroleum plants), the NBIC NB-23, which is not mentioned so far, is used for all kinds of plants. A satisfactory replacement of the corrosion liner on the subject vessel may be accomplished with the Repair an Alteration section Part 3 of the NB-23.

The rules given in the Section VIII-1 may be used for reference only as they are for new pressure vessels. The PCC-2, an ASME publication, provides guidelines based on experience in plant operations. Its rules are not mandatory like a Code.
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Thangavelu
Thangavelu Kumaresan
TA Inspection Consultant at Binh Son Refining and Petrochemical Co., Ltd

Hi Muhammad,

Before going for new liner replacement, just you need to establish the Root Cause for both pinholes & crack on the weld metal. in order to avoid recurrence of same problem after your new liner put into service.
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Muhammad Tayyab Siddique
Muhammad Tayyab Siddique
Project Engineer at Fauji Fertilizer Bin Qaism Limited
Top Contributor

ASME PCC-2 does not provide any guidelines related to relining.

NBC NB-23 does not specify any requirements except that
"welding shall be perfomed in accordance with the requirements of the original code of construction used for pressure retaining item whenever possible"

API 510 supports Mr. Kumaresan's advice to consider requirements pertaining to outgasing base metal, hadening due to welding, preheat and interpass temperature control and PWHT.

In our case ASME BPVC Sec VIII Div 1 being code of construction does specify preheat requirement, however no PWHT. Although it does not account for atomic hydrogen migration due to prolonged service.

HOWEVER, all these considerations can be bypassed by using overlap joint method for installation of lining. This method would required tack welds and plug welds between liner and vessel. Seal welds would be between fresh liner sheets not prone to hydrogen related issues.

Please refer page 7 for details of overlap joint method.
http://www.nickelinstitute.org/~/Media/ ... 10039_.pdf

We have succesfully used this technique in other vessels. However our case is unique due to PWHT vessel and high temperature hydrogen service.
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Ashokan
Ashokan Kesavan
Consultant Engineer at YSC Engg.Services Pvt.Ltd,Technopark,Tvm.

1. Presume that "Synthesis Gas" refers to Nitrogen & hydrogen in same proportion as for NH3 (Ammonia production.) For this Pr.Vessel ,the base material used was A 212 Gr.B ,Firebox quality , high tensile strength ,Carbon-Silicon Steel plates.(Withdrawn in 1967; replaced by A515 from 1968 edition of ASME UPV Code Sec.II,)

1. Strip lining with 3mm thick S.S.304L is not recommended(per a reputed Client Std) for -

(i) application with Max.design temp.above 427 deg.C
(ii) If PWHT is required after installation of the lining.
(iii) for Hydrogen service.
From details given ,it appears that all above conditions are prevalent; which require Clad(corrosion resistant) plates or Weld overlay , rather than Strip lining.
1. Width of strip should be a maximum of 100 mm ; and length could be 750 to 1000 mm.

* air pressure test shall be done by installing a 1/8" dia. tapped nipple in the lining and tested with dry inert gas at 5 to 10 psi, to detect any leaks through welds, with soap solution.

5. If potential corrosion problems of attachment welds are due to weld dilution , the lap welded method of lining may be considered..
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Re: Relining of post weld heat treated vessel.

Postby tayyabeme » 05 Jul 2014, 11:05

Is there any code reference / recommendation for selection between strip lining / cladding and overlay. That is the only way i can convince management to go for costlier options like cladding or overlay....
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Re: Relining of post weld heat treated vessel.

Postby 999 » 05 Jul 2014, 11:23

API 510 calls to follow ASME construction code for any requirements about welding, pre-heating and PWHT. We don't need to refer to any other code other than the construction one for PWHT requirements of a vessel welding repair job. However, for other requirements, API 510 or NBIC is the reference in-service code for pressure vessels designed and constructed to ASME codes.
ASME doesn't call for PWHT for the welding required to do the liner repair. Please refer to UCS-56 Note (c)(5).
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Re: Relining of post weld heat treated vessel.

Postby ben » 05 Jul 2014, 11:31

tayyabeme wrote:Is there any code reference / recommendation for selection between strip lining / cladding and overlay. That is the only way i can convince management to go for costlier options like cladding or overlay....


Installation of austenitic stainless steel liner in hydrogen service is a common practice.
I know one reference from API 941 where using of liner has been suggested as below:

"The recommended maximum hydrogen partial pressure at
atmospheric temperature for carbon steel fabricated in accordance
with the ASME Boiler and Pressure Vessel Code is
13,000 psia (90 MPa). Below this pressure, carbon steel
equipment has shown satisfactory performance. Above this
pressure, very little operating and experimental data are available.
If plants are to operate at hydrogen partial pressures that
exceed 13,000 psia (90 MPa), the use of an austenitic stainless
steel liner with venting in the shell should be considered."
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