Setiawan, Angga (2016) Analisa Kegagalan Poros Pompa Centrifugal Multistage (GA101A) Sub-Unit Sintesa – Urea PT. Petrokimia Gresik. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Amonia Feed Pump GA101A merupakan pompa jenis
centrifugal multistage dan merupakan salah satu critical equipment
pada pabrik urea PT. Petrokimia Gresik. Kegagalan yang terjadi
pada pompa GA101A adalah patahnya poros (shaft fracture).
Pemicu patahnya poros adalah modifikasi geometri ring dan poros
yang menyebabkan perubahan clearance serta penggantian
material ring dari stainless steel 410 menjadi 304. Disisi lain,
thermal expansion material yang terjadi antara ring dan poros
melampuai batas clearance yang ada, ditambah dengan adanya
vibrasi berlebih yang membuat poros dan ring bergesekan dan
menyebabkan temperature sekitar meningkat, sehingga
menyebabkan ring mengunci (locking) poros pada saat beroperasi.
Patah poros pompa dianalisa dengan melalui beberapa
tahapan, yaitu pengamatan pola patahan secara makroskopis,
melakukan pemodelan menggunakan program CAD, kemudian
melakukan analisa thermal expansion menggunakan metode Finite
Element Analysis (FEA). Analisa thermal expansion yang
dilakukan yakni dengan membandingkan material ring sebelum
dan sesudah modifikasi serta mengetahui thermal expansion yang
terjadi pada poros. Setelah itu, dihitung sisa clearance yang ada
dengan adanya pemuaian material poros dan ring.
Dari analisa didapatkan mekanisme yang menyebabkan
poros pompa GA101A patah, yaitu vibrasi tinggi pada pompa yang
menaikkan temperatur ring dan melebihi tempeartur kerja pompa.
Saat suhu mencapai sekitar 200oC, gesekan akan semakin besariv
bahkan menurut spektrum warna pada poros, suhu mencapai
sekitar 1227oC sebelum poros putus. Temperatur akibat gesekan
menyebabkan ekspansi material kedua komponen, sehingga ring
mengunci poros hingga akhirnya patah. Langkah preventif dari
hasil analisa adalah memperbesar clearance poros-ring sebesar
0.40mm tanpa mengganti jenis material, yakni stainless steel 304,
sedangkan jika dengan material 410 clearance minimal yang
dibutuhkan adalah sebesar 0.35mm
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Ammonia Feed Pump GA101A is a centrifugal multistage
pump and one of the critical equipment in urea plant PT.
Petrokimia Gresik. Failure that occurs on GA101A pump is shaft
fracture. Geometry modification on ring and shaft influenced shaft
fracture and affected clearance changing, also material on ring was
changed from stainless steel 410 to 304. On the other hand,
material thermal expansion between ring and shaft overreached the
existing clearance, coupled with excessive vibration which made
shaft and ring on friction and caused temperature around rising. As
a result, locking ring on shaft occurred.
Pump shaft fracture is analyzed through several stages,
namely macroscopic analysis on fracture pattern, modelling on
CAD software, thermal expansion analysis using Finite element
analysis (FEA). Thermal expansion analysis is done by comparing
the ring material before and after modification as well as determine
the thermal expansion that occurs on the shaft. After that, the rest
of existing clearance is calculated by thermal expansion of the shaft
and the ring material.
The analysis found that the mechanism that cause shaft
fracture on GA101A pump shaft is high vibration on pump that rise
the temperature on ring and shaft area which is beyond the working
pump temperature. When the temperature reached around 200oC,
friction would be greater and according to the spectrum thatvi
identified on shaft, the temperature reached 1227 oC before shaft
fracture. Friction temperature cause material thermal expansion on
both component, then locking ring on shaft occurred before shaft
fracture. Preventive action that needs to take according to the
analysis is enlarging the amount of clearance between ring and
shaft to 0.40mm without changing the type of material, namely
stainless steel 304 or using material 410 with minimum clearance
0.35mm
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Additional Information: | RSM 620.112 Set a |
| Uncontrolled Keywords: | Centrifugal Multistage Pump, Finite Element Analysis, Thermal Expansion |
| Subjects: | T Technology > TJ Mechanical engineering and machinery |
| 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 01:31 |
| Last Modified: | 23 Apr 2020 01:31 |
| URI: | http://repository.its.ac.id/id/eprint/75883 |
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