Analisa Kegagalan Pipa Udara A312 Tipe 304H Pada LINE A-1011-14” (25P2J) Unit Amonia PT.Petrokimia Gresik

Prayoga, Sopan (2016) Analisa Kegagalan Pipa Udara A312 Tipe 304H Pada LINE A-1011-14” (25P2J) Unit Amonia PT.Petrokimia Gresik. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Line A-1011-14”(25P2J) menggunakan pipa tahan karat TP304H berdiameter 14 inch. Pipa mengalami pecah saat beroperasi pada temperatur 800oC (overheating) dan crack ditemukan pada hampir semua sambungan las. Masalah ini telah diteliti departemen Inspeksi PT.Petrokimia Gresik. Hasil analisa pihak petrokimia yaitu kegagalan terjadi karena pre-existing crack pada lasan longitudinal sebesar 80% tebal pipa, dan overheating hanya mempercepat terjadinya kegagalan. Akan tetapi pihak PT.Petrokimia membutuhkan analisa lainnya untuk menemukan akar penyebab kegagalan. Pipa udara merupakan jenis stainless steel dan beroperasi pada temperatur 610oC, dimana pada temperatur tersebut stainless steel akan mengalami sensitasi. Kegagalan pipa dievaluasi dengan metode RCFA (root cause failure analysis) didukung pengujian Metalografi, SEMEDX, dan OES. Metode ini digunakan untuk mengetahui akar penyebab kegagalan pipa udara TP304H pada line A-1011- 14”(25P2J). Hasil analisa didapat adanya pre-existing crack mengakibatkan tegangan pipa 12978.55 psi masih belum melampaui tensile strength material TP304H pada temperatur 800oC yaitu 18000 psi. Hasil pengujian SEM dan metalografi menyatakan bahwa, kegagalan yang terjadi pada las longitudinal diakibatkan adanya IGSCC (intergranular stress corrosion cracking) yang mengakibatkan batas butir menjadi lemah danii mengalami sliding, dan terjadi penurunan kekuatan pada material. Adanya sensitisasi dibuktikan dengan pengujian EDX yang menunjukkan kenaikan persentase unsur krom dan karbon pada batas butir HAZ yaitu 1.4% dan 21.64%. Untuk menghindari kegagalan yang sama, maka material TP304H welded pipe perlu diganti TP304H seamless pipe. Crack yang terjadi pada las circumferential diakibatkan adanya IP (incomplete penetration) yang menyebabkan tumbuhnya crack yang menjalar dari ujung IP menuju fusion zone, untuk mencegah hal tersebut maka setiap proses pengelasan yang dilakukan harus disesuaikan dengan prosedur ======================================================================================================== Line A-1011-14 "(25P2J) using a stainless steel pipe TP304H with a diameter of 14 inch. Pipe rupture during operation at temperatures of 800oC (overheating) and a crack was found in almost all of the weld joint. This issue has been studied by Inspection Departement of PT.Petrokimia Gresik. The results of analysis of PT. Petrokimia Gresik, are a failure occurred because of pre-existing crack in longitudinal weld pipe thickness by 80%, and overheating is only accelerate the occurrence of failure, but PT. Petrokimia Gresik need more analysis to find the root cause of the failure. Air pipe is a type of stainless steel and operate at a temperature of 610oC, at that temperature stainless steel will occur sensitization. A pipe failure was evaluated with RCFA (root cause failure analysis) method which is supported with Metallographic testing, SEM-EDX and OES. This method use to understand root cause of failure of air pipe TP304H in line A-1011-14 "(25P2J). The result of analysis shows existence of pre-existing crack resulting pipe stress is 12978.55 psi which not exceeds yield strength of TP304H material at temperature of 800oC ,are 18000 psi. A test results of SEM and metallographic states that, failure that occurred in longitudinal weld due to their IGSCC (intergranular stress corrosion cracking) which results in grain boundaries become weak and sliding occurs, and occured strength reduction to material. The existence of sensitization is evidencediv with EDX tests indicating a high chrome and carbon elements at grain-boundary ,are 1.4% and 21.64%. To avoid same of failure, so TP304H welded pipe material needs to replaced with TP304H seamless pipe. Crack that occurs in circumferential weld caused by the incomplete penetration that causes growth of crack that extends from the end of IP to the fusion zone, to prevent that then any welding process is carried out should be adjusted procedure

Item Type: Thesis (Undergraduate)
Additional Information: RSM 621.867 2 Pra a
Uncontrolled Keywords: 304H, failure analysis, high temperature, precipitates.
Subjects: T Technology > TJ Mechanical engineering and machinery > TJ930 Pipelines (General). Underwater pipelines.
Divisions: Faculty of Industrial Technology and Systems Engineering (INDSYS) > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User: Mr. Tondo Indra Nyata
Date Deposited: 23 Apr 2020 01:50
Last Modified: 23 Apr 2020 01:50
URI: https://repository.its.ac.id/id/eprint/75885

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