Fwd: [Oil&Gas] Pipeline Welding Process - Full GTAW

 

Ma'af maksudnya pada paragraph saya paling bawah clause 434.8.5 ASME B31.4

 

Salam,

 

d;Art

---------- Forwarded message ----------
From: Dirman Artib <dir.art@gmail.com>
Date: Tue, Nov 15, 2011 at 10:03 AM
Subject: Re: [Oil&Gas] Pipeline Welding Process - Full GTAW
To: Migas_Indonesia@yahoogroups.com

Ingak-ingak......

Mengelas dgn FCAW di oil &gas practices banyak keterbatasan

 

Saya cuplikan dari API RP 582 di bawah ini.

 

5.2.5 FCAW

5.2.5.1

Self-shielding FCAW (FCAW-S) may be used only for welding carbon steel structural items. The following

guidelines and restrictions apply:

a) electrode types identified by the consumable manufacturer for multipass application should be used,

b) only electrode classifications which have specified minimum impact test requirements should be used,

c) FCAW-S shall not be used with other welding processes without qualifying the specific combination.

5.2.5.2

FCAW with external gas shielding (FCAW-G) may be used for either groove or fillet welds for pressure

boundary or structural welding.

5.2.5.3

For procedures requiring either impact or hardness testing, it is advisable to review weld metal properties

with the consumable manufacturer to ensure the original qualified properties continue to be met. When rutile type (i.e.

E71T-1 type) electrodes are used as-welded or in the postweld heat treated (PWHT'd) condition with impact testing

required, the specific brand and trade name electrode used in production must be qualified on supporting PQRs with

impact test results meeting the minimum design code requirements.

COMMENTARY Welding consumables, including those for FCAW, are routinely used in situations not addressed

by the testing requirements in AWS/ASME welding specifications. A periodic review with the manufacturer is good

practice to assure minor variations that occur over time with FCAW consumable formulations (e.g. raw material and

microalloying changes) do not adversely affect the ability of these products to perform as intended. Small changes in

microalloying additions can have significant effects on properties.

5.2.5.4

Welding consumables shall be limited to the ASME/AWS classification used in the PQR.

5.2.5.5

For welding pressure-containing equipment wall thickness in excess of 3/8 in. (9.5 mm), the diffusible

hydrogen limit for FCAW electrodes (as manufactured) shall meet the specifications in Table 2.

Table 2—Diffusible Hydrogen Limit for FCAW Electrodes

Specified Minimum Tensile Strength for the Base Metal Maximum Diffusible Hydrogen Designation

(per ASME/AWS SFA/A5.20 or SFA/A5.29)

≤

70 ksi (483 MPa) H16

>

70 ksi (483 MPa) and ≤ 85 ksi (587 MPa) H8

>

85 ksi (587 MPa) H4

Ini Pipeline melintasi lokasi apaya ?

Apa inaccessible atau tidak (sungai, danau, tempat keramaian...etc) , karena menurut clause 434.8.5 jika melewati lokasi tsb. maka RT minimum adalah 90%.

 

Salam,

 

d'Art.(Pemantau Diskusi Welding)

 

 

2011/11/15 DARMAYADI <darma_yadi@yahoo.com>

 

Pak Aip,

Untuk menentukan proses las yang digunakan, salah satu yang perlu bapak pertimbangkan adalah lokasi pengerjaan.

Untuk pekerjaan di luar ruangan, sebaiknya dihindari penggunaan proses yang memerlukan bantuan gas sebagai pelindungnya ( seperti : GTAW atau FCAW/GMAW ), bapak bisa ganti ke proses SMAW.

Banyak problem yang akan timbul disekitar sambungan lasnya jika dipaksakan menggunakan proses yang butuh gas.

Demikian

Salam

Darmayadi

---

Dari: Aang <aangk@yahoo.com>
Kepada: "Migas_Indonesia@yahoogroups.com" <Migas_Indonesia@yahoogroups.com>
Dikirim: Senin, 14 November 2011 13:26
Judul: [Oil&Gas] Pipeline Welding Process - Full GTAW

.

All,

Mohon bantuan advice-nya...

 

Saat ini kami sedang mengerjakan Diesel PipeLine 4 in sepanjang 14km. Material pipa yang digunakan adalah ASTM A106 Grade B dengan Schedule 80 (XS): 8mm thick. Saat ini kontraktor sudah mengajukan 1 WPS yaitu Root & HotPass (2 Layer) menggunakan GTAW dan Filler & Caping (2 Layer) menggunakan FCAW. Karena kesulitan peralatan dan manpower, kontraktor mengajukan kembali WPS baru yaitu Full GTAW.

 

 

QC yang kami lakukan adalah Visual Welding dan NDT/RT 10% dari seluruh Join. Karena RT hanya 10%, kami minta saran dan pengalamannya menggunakan full GTAW untuk join Pipeline, apakah dari sisi kualitas lebih baik dari gabungan GTAW + FCAW? Apa saja yang menjadi concern dengan full GTAW ini?

 

Atas bantuannya, terima kasih.

 

Salam,

aiv

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