In -service welding on HP Gas line, prior to Hot Tapping. Need immediate suggestions.

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Venkatachalam Govindan

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Mar 9, 2021, 10:10:21 PM3/9/21
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Dear Respected ones, 

We are planning a hot tapping on the HP gas line, which is 30" dia, and thickness 15mm, and carbon steel material. 

Around 15-meter length, where both the ends are closed by check valves. 

The line is isolated, we want to weld a 2" dia ventilate on the 30" pipe.

There is no flow is possible. We have to complete this work at any cost, the client says. Is this okay for you? it can be safe? 

Due to 15mm thickness, we are planning to do by 2.5mm, E 7018 electrode by the lower current. 

Please advise, any vapor cloud will be an issue inside the pipe? or we can do it because thick ness is high?  or shall we ask for at least a minimum flow so the vapor cloud will not be there. 

Looking sincerely your support friends. 

For your information, we regularly do such hot tapping works, at 800PSI pressure, but, with the flow. 04m/s. 

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Venkatachalam Govindan
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Mobile +965-97604989

james gerald

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Mar 10, 2021, 1:32:20 AM3/10/21
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Few steps to consider as below.

1. First determine the actual thickness existing on the pipe where 2' ventilate to be attached by performing UT Thickness Gauging.
2. Based on the thickness consider the viability of performing an Hot Tap, Normally 6.5mm minimum is considered viable.
3. Based on the AWS formula calculate the Peak temperature attained at the inner side of the pipe.
4. Another option is to conduct a Mock-up test using the same condition and measure the inner side peak temperature by attaching a Thermocouple.
5. Based on the actual process fluid scale, consult the process engineer the effects of Flash point of the actual Fluid with respect to the inner side peak temperature calculated or simulated.
7. Also consult your process engineer with respect to the vapour cloud.


With respect to the effects of welding,

1. Higher thickness helps in fast heat conduction and hence inner side peak temperature may increase.
2. This can be combated by increasing Heat Input during welding or preheat if permitted.
3. Normally hot tap mockup would provide you with actual situation

Thanks & Regards

J.Gerald Jayakumar




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Venkatachalam Govindan

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Mar 10, 2021, 10:09:37 PM3/10/21
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Attn: J.Gerald Jayakumar

Dear Sir, 

Thank you so much for your sincere response. We are worried about no flow in the pipe because isolated by check valves on both sides. Another worry the client doubt about valve may have passing so. 

Anyhow have decided now, one line can do with Nitrogen purging and another line with a minimum of at least 10% of the crack opening flow. Hope things will be better. 

We afraid of the vapor cloud but there is flow now so it could be safe we believe and planning the execution next week. 

Still, we are looking for a suggestion from anyone on their own experience about in-service welding can be possible without flow inside the pipe? in such an isolated pipeline. 

Best Regards, 

Venkat G. 

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/1306834709.879538.1615356024823%40mail.yahoo.com.

Ramzi Ben Ahmed

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Mar 11, 2021, 3:41:02 AM3/11/21
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can you send us some picture about it

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Customer Care

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Mar 11, 2021, 10:20:18 PM3/11/21
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Dear,
Please check API 2201 Hot Tapping
Regards, 
Ramon Briceno.



Enviado desde mi smartphone Samsung Galaxy.


-------- Mensaje original --------
De: Venkatachalam Govindan <vin...@gmail.com>
Fecha: 2021/03/09 11:10 PM (GMT-04:00)
Asunto: [MW:32036] In -service welding on HP Gas line, prior to Hot Tapping. Need immediate suggestions.

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Customer Care

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Mar 11, 2021, 10:20:18 PM3/11/21
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Dear, 
One standard API describe all the technical procedures to realice this work. Let me check it and I will send You the reference.
Regards,
Ramon Briceno.



Enviado desde mi smartphone Samsung Galaxy.


-------- Mensaje original --------
De: Ramzi Ben Ahmed <ramzibe...@gmail.com>
Fecha: 2021/03/11 4:41 AM (GMT-04:00)
Asunto: Re: [MW:32039] In -service welding on HP Gas line, prior to Hot Tapping. Need immediate suggestions.

pgos...@rogers.com

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Mar 11, 2021, 11:10:11 PM3/11/21
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Hi,

Hot tap is very frequently applied on pipelines and piping carrying hydrocarbons. Hydrocarbons are flammable, explosive. Traces of hydrocarbons can easily introduce flames and fires. Hence safe operating procedures, knowledge base of personnel frequently doing this work are important. You need to check with your operations personnel on the best and safest way for hot tapping.

 

API 2201 provides exhaustive information on Hot Tapping. In fact, its’ the industry document for his technique of “in situ alterations/ modifications in pipelines. There’re many checklists, points to be considered for safe hot tapping work. I’ve attached some extracts and highlighted texts from this document.

 

It’s advisable to avoid any flow of gases/ hydrocarbons during hot tapping.

 

I hope the attached information would be of help.

Thanks.

 

Pradip Goswami.P.Eng, IWE.

Independent  & Consulting Welding & Metallurgical  Engineering Specialist

Saudi Aramco Approved Designated Welding Engineer(DPWR)

Linkedin: https://www.linkedin.com/in/pradip-goswami-2999855/

Email:pgos...@rogers.com,pradip....@gmail.com

Cell/Whasapp:1-905-9793232

 

From: material...@googlegroups.com <material...@googlegroups.com> On Behalf Of Venkatachalam Govindan
Sent: March 9, 2021 8:18 AM
To: material...@googlegroups.com
Subject: [MW:32036] In -service welding on HP Gas line, prior to Hot Tapping. Need immediate suggestions.

 

Dear Respected ones, 

 

We are planning a hot tapping on the HP gas line, which is 30" dia, and thickness 15mm, and carbon steel material. 

 

Around 15-meter length, where both the ends are closed by check valves. 

 

The line is isolated, we want to weld a 2" dia ventilate on the 30" pipe.

 

There is no flow is possible. We have to complete this work at any cost, the client says. Is this okay for you? it can be safe? – You need to have a check of any remaining gases, vapor, with Tracers

 

Due to 15mm thickness, we are planning to do by 2.5mm, E 7018 electrode by the lower current. 

 

Please advise, any vapor cloud will be an issue inside the pipe? or we can do it because thick ness is high?  or shall we ask for at least a minimum flow so the vapor cloud will not be there. 

 

Looking sincerely your support friends. 

 

For your information, we regularly do such hot tapping works, at 800PSI pressure, but, with the flow. 04m/s. 

 

--

Venkatachalam Govindan

QHSE Lead | Auditor | Trainer

(API U Trainer | IRCA Lead Auditor | Exemplar Global MS Specialist |CQI Practitioner)

Mobile +965-97604989

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API 2201 2010-Extracts.pdf

CHITTARANJAN BHIWANDKAR

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Mar 12, 2021, 4:47:47 AM3/12/21
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Pls. see that the isolated portion is made gas free & certificate from explosive inspector is obtained before doing any hot work or grinding. 

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/CAH5TVhasyAEcOUniDtcKqKAk0Nqo9Cu3DyO%2BJwwRsFJxeLeqQA%40mail.gmail.com.

Venkatachalam Govindan

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Mar 12, 2021, 5:20:08 AM3/12/21
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Dear Ramon,

Thanks, obviously I will look for compliance of the API 2201.

Best Regards,

Venkat G

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james gerald

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Mar 12, 2021, 5:20:16 AM3/12/21
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Dear Mr. Venkat G,

I have a doubt, is the vapour cloud mentioned in your mail is it the welding Fumes formed during Hot Tap.

Thanks & Regards

J.Gerald Jayakumar


Sudhakar Kuppuswamy

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Mar 12, 2021, 6:20:38 AM3/12/21
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Also , consider the following, 

For welding , use only SMAW process as it is low heat intensity process and welding using 2.5 mm dia electrode and even small dia meter electrode. 

I presume, the joint type is branch fitting connection type, not the split tee type . 

If it is branch fitting type the amount of welding to be deposited will be very less and same shall be carried out on a specific area on the run pipe. So amount of welding and time taken for welding shall be less. 

To weld a buttering layer required to fix a 2 inch branch on a run pipe is relatively less when compared with a split tee type. 

Regards,
Sudhakar K



On Fri, 12 Mar 2021 at 3:09 PM Sudhakar Kuppuswamy <sudhak...@gmail.com> wrote:
Hi,

As you have mentioned in your email already , it is always recommended to carry out Hot-TAP welding with a certain amount of minimum flow. 

In this case, the run pipe thickness is 15 mm. So,the risk is really low. Just recently, we qualified a HOT-PQR with 7.9 mm thickness and while buttering pass the maximum inside temperature on run pipe found is 350 Deg C .

I suggest you the following ,

Discuss with the process safety engineering team and seek advise on the maximum allowable inside temperature that is acceptable while welding(1st pass I.e buttering and 2nd pass mainly) 
They ll advise based on flash and fire point and internal pressure built up due to gas expansion and so on.

Also, check  the feasibility for nitrogen purging  the line during welding. 

Regards,
Sudhakar K 

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Regards,

Sudhakar K CEng MWeldI,IWE.

Welding & Metallurgical Engineer,

Email: sudhak...@gmail.com.

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Sudhakar K CEng MWeldI,IWE.

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Email: sudhak...@gmail.com.

Sudhakar Kuppuswamy

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Mar 12, 2021, 6:20:46 AM3/12/21
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Hi,

As you have mentioned in your email already , it is always recommended to carry out Hot-TAP welding with a certain amount of minimum flow. 

In this case, the run pipe thickness is 15 mm. So,the risk is really low. Just recently, we qualified a HOT-PQR with 7.9 mm thickness and while buttering pass the maximum inside temperature on run pipe found is 350 Deg C .

I suggest you the following ,

Discuss with the process safety engineering team and seek advise on the maximum allowable inside temperature that is acceptable while welding(1st pass I.e buttering and 2nd pass mainly) 
They ll advise based on flash and fire point and internal pressure built up due to gas expansion and so on.

Also, check  the feasibility for nitrogen purging  the line during welding. 

Regards,
Sudhakar K 
On Wed, 10 Mar 2021 at 7:10 AM Venkatachalam Govindan <vin...@gmail.com> wrote:
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Venkatachalam Govindan

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Mar 14, 2021, 11:42:30 PM3/14/21
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For many years this line was closed on both sides by check valves, and now operations must provide a drain for both the inlet and the outlet.  Therefore, since the functions are line isolated they cannot open the valves for flow.  They thought about the vapor-cloud of fuel inside the pipe because they suspected it might pass through the valves on both sides.  Gas oil is inside the fuel. 

Finally, the operations agreed to convert from drain to vent.  Now they agree to open the crack to 10% flow.  I hope things will be fine now because there is enough thickness.  Thank you for all your support and guidance.

Best Regards,

Venkat G.

On Fri, 12 Mar 2021 at 2:37 PM, Venkatachalam Govindan <vin...@gmail.com> wrote:
Yes, we doing nitrogen purging. Thanks for your details with the experiment. 

Best Regards,

Venkat G

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anjansaini

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Mar 14, 2021, 11:42:30 PM3/14/21
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Hi
someone from saudi aramco should help, they have a procedure including min/max parameters to monitor/consider for hot tap.

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/824951860.93338.1615544357733%40mail.yahoo.com.

Venkatachalam Govindan

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Mar 14, 2021, 11:42:30 PM3/14/21
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Yes, we doing nitrogen purging. Thanks for your details with the experiment. 

Best Regards,

Venkat G
On Fri, 12 Mar 2021 at 2:20 PM, Sudhakar Kuppuswamy <sudhak...@gmail.com> wrote:

Sudhakar Kuppuswamy

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Mar 15, 2021, 12:26:35 AM3/15/21
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Then there should not be problem . What  is the nitrogen purge flow rate that is planned ? 

Venkatachalam Govindan

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Mar 15, 2021, 2:17:40 AM3/15/21
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Dear Sudhakar,

Good day.

We may start the process probably within the next couple of weeks. I will update you with all the status with the appropriate pictures, once have done.

Thank you to everyone in this group. All the very best, and

Best Regards,

Venkat. G



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