Procedimiento Reparacion Tubo-placatubular

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ALSTOM Power Energy Recovery GmbH

34123 Kassel, Ellenbacher Str. 10

Germany

Repair Procedure

Dokument-Nr:Document-No.:

1 02 123-81-14-D4

Seite vonPage of2 14

Repair of tubes to tubesheet weld at inlet side and outlet side ofFire Tube Boiler

General

At the tube to tubesheet welds on the gas inlet and outlet side of the fire tube boiler

leakages occurred in the weld.

Grinding of surface and PT have been performed. Most likely location of pores is at

the welding end craters.

As conclusion it was decided that all welds shall be removed and rewelded acc. to this

procedure.

Repairing tools and repairing material are described in Appendix 3.

The work will be done acc. to NBIC, which will be used due to the fact that the boiler

was already in operation.

Preconditions

Tube sheet and tubes should be clean and dry. The tubes should be dried and cleaned

with compressed air.

The following tasks should be confirmed before the repair:

AI approval of repair procedure is mandatory

Tube sheet is clean and dry

All electrical equipment of boiler has connected with safety protectors.

Axial-flow fans have been installed on the inlet and outlet of the boiler and the

boiler is ventilated.

Kick-off meeting to the participants of each procedure. Work may proceed after

release from Outotec.

The required welders must have the satisfied TIG qualifications and the welding job

should be strictly done according to WPS A148Re offered by ALSTOM.


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1. Preparation of the tube sheet for repairTwo different repair methods are applied for the repair of tube to tubesheet welds.

Para. 1 a. describes the procedure for a local area which was already repaired

whereas para 1 b. describes the repair for all other tube to tube sheet welds.

1. a. repair in the 2 areas which showed leakage during hydrotest on

9.9.11

- Both of the leaking tubes shall be cut for testing purposes. Detailed cutting

procedure still has to be agreed on. For repair please refer to 1 02 123-81-13-

D4-01.

Sketch 1: repaired area acc to procedure 1021213-81-13-D4


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1. b. check and repair of all other welding seams

- Repair of tube sheet welds will be performed in clusters of 9 tubes each.

- Distance between clusters are maximized. The minimum distance between 2

clusters is 5 x tube pitch (see sketch 2 and 3)

- As maximum 4 clusters at one time will be ground and rewelded

- Remove inner layer of refractory at a length of 500 mm if needed for working

space of milling machine- Cut and remove Pos. no. 51 on drawing 102123-33-11-Z0-01

- Grind back the tube projection to 4,5 mm for tubes 60,3 x4,5 mm

- Grind back the tube projection to 6 mm for tubes 101,6 x 8 mm mm

- Grind back the total weld by using milling machine. Cutting tool should be used

to prepare the original J-groove acc. drawing no. 05685 (Fire tube boiler

details 1).

- After removing of welds 100% VT and 100% PT inspection should be done at the

machined area

-Welding of tube to tube sheet acc. drawing no 05685 and WPS A148Re.


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Sketch 2: Repair - Clusters


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Sketch 3: Repair - Clusters


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2. Welding and Testing

- Preheating of a min. surface of 250 mm around the repair place at a

temperature of min. 150 C 220 C

- Root pass welding acc. to WPS A148Re

- Testing: 10% PT, 100% VT of root pass (only for the first 200 welds)

- Build up welding acc. to WPS A148Re

- Maximum interpass temperature is 232 C

- Testing 100% PT, 100% VT

- Referring NBIC, part 3, sect. 2 para. 2.5.3 and 2.5.3.1 the welding method

without PWHT will be applied

- Hydrotest: After completion of all welds

NOTE: after root pass testing of the first 200 welds it needs to be agreed if the

remaining welds can be welded completely without root pass testing.

3. (deleted, see 2)

4. Reinstallation of Pos. 51 and refractory

Reweld pos. no. 51 acc. To WPS A356


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Appendix 1 WPS and PQR for Tube to Tubesheet Welding


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Appendix 2: WPS and PQR for welding of Pos. No. 51


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Appendix 3: Required Tools and Materials

Material

- TIG wire DMO IG 2,4 mm, 200 Kg- CM2- IG 2,4 mm, 4 Kg

Tools

-

1 x rolling machine for inner

51,3 mm (not planned, just as precaution)

- 1 x bevelling machine for inner 51,3 mm (not planned, just as precaution)

- 1 x drift punch outer 60 mm, inner 51,3 mm, length400 mm (not planned,

just as precaution)

- 2 x milling machine (rotary speed ~ 20.000 rpm) with 8 and 6 mm adaptor

- various milling cutter tree shape 8 mm

- 1 x hammer ~ 2.000 gr

- 2 x TIG welding machine with tungsten electrodes 2,4 mm

- 2 x argon 99,8%

- various nos. of cleaner

- 2 x grinding machine for grinding disc 115 mm

- various grinding discs 115 mm

- various cutting discs 115 mm

- various serrated grinder grain size 40

- various grinding paper grain size medium

Procedimiento Reparacion Tubo-placatubular

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