HELIUM LEAK DETECTION PROCEDURE HDO/HELIUM /01 Dt: 29.07.2010 1) Scope of Work: Helium leak testing ofShell side of Tube to tube sheet joint for the HEAT EXCHANGERS Client: TOYO ENGINEERING CORPORATION (Job No:8134 – Item No.023-E-014, Job No:8135A/B – Item No.023-E-040A/B). PO NO: FOA NO. 6270/F/031 DT: 05-04-2010 Code: ASME Section V, Article10 – (Hood Technique-pressure mode) 2) Equipment: a) Mass Spectrometric Helium leak detector. The sensitivity of this leak detector is better than 1 X 10 -9 Std cc/sec. b) Calibrated standard leak with leak rate 2.6 x10 -8 Std cc/sec. c) Calibrated standard leak with leak rate 3 x 10 -6 Std cc/sec. 3) Acceptance standard : If the leak detector will show leak rate of helium from tube to tube sheet joints of the HEAT EXCHANGER, When shell side filled with helium/Nitrogen mixture (Concentration 10/90 percentage) up to a pressure of 25% of Design pressure in the shell, If it is less than 1 x 10 -6 Std cc/sec, it will be accepted. 4) Procedure : The following procedure will be adopted to find out the leak rate of the Heat Exchanger. (A) Shell side Test: TUBE TO TUBE SHEET JOINT (1) The helium leak detector will be calibrated with the standard leak. Then the calibrated standard leak wil be removed. (2) The sniffer probe will be connected to the leak detector and the sensitivity will be verified using a Calibrated standard leak with leak rate 3 x 10 -6 Std cc/sec. (3) The test pressure shall be 25% of design pressure. The shell will be filled with nitrogen up to a pressure of 90% (25% of design pressure) and then filled with helium 10% (25% of design pressure). (4) The soaking period after filling shall be 60 minutes, (5) The tube to tube sheet joints will be covered by thick polythene/plastic sheets. (6) The volume covered by the sheet will be connected to the sniffer of the leak detector. (7) If there is leakage through tube to tube sheet joints, the content of helium gas in cover will be sensed by the helium leak detector. (8) Total leak rate through tube to tube sheet joints, to the region enclosed by the polythene/plastic sheets will be measure. (9) If the leak rate is less than 1 x 10 -6 Std cc/sec , the heat exchanger passes the above test, it will be accepted. (10)If the leak rate is more then 1 x 10 -6 Std cc/sec, repair tube to tube sheet joint and retest, Repeat the above procedure for retest and measure leak rate, which should be less than 1 x 10 -6 Std cc/sec .Then the heat exchanger passes the above test, it will be accepted. HINDUSTAN DORR-OLIVER LTD. DNV TOYO

Helium Leak Test for Heat Exchangers

Download PDF Report

Upload
jdfdferer
View
307
Download
24

Embed Size (px)

DESCRIPTION

Summary of Helium Leak Test

Citation preview

Page 1: Helium Leak Test for Heat Exchangers

HELIUM LEAK DETECTION PROCEDURE

HDO/HELIUM /01 Dt: 29.07.2010 1) Scope of Work:

Helium leak testing ofShell side of Tube to tube sheet joint for the HEAT EXCHANGERS

Client: TOYO ENGINEERING CORPORATION

(Job No:8134 – Item No.023-E-014, Job No:8135A/B – Item No.023-E-040A/B).

PO NO: FOA NO. 6270/F/031 DT: 05-04-2010 Code: ASME Section V, Article10 – (Hood Technique-pressure mode) 2) Equipment:

a) Mass Spectrometric Helium leak detector. The sensitivity of this leak detector is better than 1 X 10

-9 Std cc/sec.

b) Calibrated standard leak with leak rate 2.6 x10-8

Std cc/sec. c) Calibrated standard leak with leak rate 3 x 10

-6 Std cc/sec.

3) Acceptance standard :

If the leak detector will show leak rate of helium from tube to tube sheet joints of the HEAT EXCHANGER, When shell side filled with helium/Nitrogen mixture (Concentration 10/90 percentage) up to a pressure of 25% of Design pressure in the shell, If it is less than 1 x 10

-6 Std cc/sec, it will be accepted.

4) Procedure :

The following procedure will be adopted to find out the leak rate of the Heat Exchanger. (A) Shell side Test: TUBE TO TUBE SHEET JOINT

(1) The helium leak detector will be calibrated with the standard leak. Then the calibrated standard leak wil be removed.

(2) The sniffer probe will be connected to the leak detector and the sensitivity will be verified using a Calibrated standard leak with leak rate 3 x 10

-6 Std cc/sec.

(3) The test pressure shall be 25% of design pressure. The shell will be filled with nitrogen up to a pressure of 90% (25% of design pressure) and then filled with helium 10% (25% of design pressure).

(4) The soaking period after filling shall be 60 minutes, (5) The tube to tube sheet joints will be covered by thick polythene/plastic sheets. (6) The volume covered by the sheet will be connected to the sniffer of the leak detector. (7) If there is leakage through tube to tube sheet joints, the content of helium gas in cover will be

sensed by the helium leak detector. (8) Total leak rate through tube to tube sheet joints, to the region enclosed by the

polythene/plastic sheets will be measure. (9) If the leak rate is less than 1 x 10

-6 Std cc/sec , the heat exchanger passes the above test, it

will be accepted. (10) If the leak rate is more then 1 x 10

-6 Std cc/sec, repair tube to tube sheet joint and retest,

Repeat the above procedure for retest and measure leak rate, which should be less than 1 x 10

-6 Std cc/sec .Then the heat exchanger passes the above test, it will be accepted.

HINDUSTAN DORR-OLIVER LTD. DNV TOYO