Sulfuric acid drum nozzle problem

[okay Tutar]

Hello everyone, I hope you all have a nıce day.

We had a problem in sulfuric acid %99 conct. drum nozzle.

After 2 years of operation, suddenly our nozzle has been failured.

We checked api 571.Concentration of acid is ok, it is %99.Speed of acid is lower than critical level.

But, when we examine flange and piping of nozzle. There is general corrosion and thickness of weld neck is thinned . Our material is carbon steel. But, in pipe thickness is not thinned.

Do you have suggestion for reason of this problem ? What could it be ?

[Vinoth kanna ramachandran]

Dear sir,

Greetings 

kindly  make sure that the pipe thickness is not thinned using DIGITAL RT if possible.  

We experienced the same problem in repair of sulphuric acid vertical mounted vessel , Carbon steel A 516  Gr B , nozzle failure . 

later we found under deposit corrosion of nozzle pipes . the we back gouged and flush grounded with E-316 for repair. 

please update , if you got better solution. 

Regards

Vinoth kanna

QC- welding & piping inspector 

Manifa Project

API -510, CSWIP 3.1, NDT level II - UT, RT ,PT, MT, VT,LT,Infrared & Thermography 

Technical - Metallurgy

Contact : M - +91-9787954338,+966-539127946

              Email id : srvk...@gmail.com

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[chandrakant mohikar]

Nozzle failed means, what exactly happened.?  if no flow through nozzle means, it is choked. it should be dechoked and material like dirt etc to be removed, another reason may be there is some other corrosive material through reverse flow. you can conduct systematically risk / HAZOP study with guidewords. if you can isolate, drain 99% H2SO4, remove nozzle and perfoem QA / TIC (testing, inspection & certification). as per design & EPC requirements, considerations & criteria. 

chandrakant mohikar

Infra Academy.
https://tinyurl.com/InfraAcademy

8446079514

  

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[Zohair.O]

Hi everyone, 

Sulfuric acid is very tricky when we talk about corrosivity because it depends on many factors ( concentration, temperature, velocity ... etc). For the concentration of 98% generally, it's better to use the SS316 instead of carbon steel for pipes, and you may use the carbon steel tanks with SS clad or overlaid nozzles. 

I thank the problem is mainly related to material selection.    

you can consult the NACE Standard related to sulfuric acid storage tank inspection. 

Z.O

[okay Tutar]

Dear zohair,

Thank you for your help! We have decided to use SS316 steel instead of carbon steel. Problem is actually because of sulphuric acid corrosion.

Kind regards,

1 Nisan 2021 Perşembe tarihinde saat 09:51:58 UTC+3 itibarıyla Zohair.O şunları yazdı: