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
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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: | http://repository.its.ac.id/id/eprint/75885 |
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