HYDROGEN ATTACK

[hyl]

HELLO
I AM BOILER ENGINER IN HARTH POWER STATION WE HAVE TWO BOILER CAPACITY 200MW THESE BOILER ARE POLUTED FROM CONDENSER LEAKAGE AND OPERATED AT HIGHT CODUCTIVITY 80 MC AND LOW PH 6.8 THE POLUTION CONTINUE FOR 18 HOUR AFTER THAT WE DO SOME TREATMENT BLOW DOWN AND PHOSPHATE INJECTION IN DRUM AND RETURN BACK TO THE NORMAL CONDITION .AFTER ONE WEEK WE GET TUBE FAILURE IN THE BOILERS FROM LAB ANLYISES WE FIND HYDROGEN ATTCK AND CORROSTION IN TUBES .
MY QUESTION .HOW MANY HOUER OF POLUTION THE HYDROGEN ATTACK TAKE PLACE (ATTACK THE TUBES)AND WOREST CASE OF POLUTION (PH & CONDECTIVITY )?
THANKX AND GODBLESS

 

[Goahead]

Why would not you perform complete metallurgical investigation on the causes of failure and on failure prevention activities?

http://www.welding-advisers.com/

 

[metengr]

hyl;
You need to immediately stop the condenser tube leaks (repair or re-tube) or you will ruin the waterside tube surfaces and prime mover. This damage mechanism occurs at operating temperature and pressure regardless of time. You should chemically clean the boiler waterwall tube circuit after you stopped the condenser leaks.

 

[hyl]

hyl
hello

i would like to express my sincerest gratitude to MR Goahead and MR metengr for their advice about the hydrogen attack and i want to inform them that all the failure tubes are infected in the corssion area in the fire side and most of them in pipes that change during the anual maintenace which is diferent from orginal tubes (SA 178 C ERW)the change tubes is (SA 210 SEAMLESS )..the question is that is the type of material and the heat treatment has effect on hydogen attack ?
thankx for reply and god bless

 

[metengr]

hyl;
No, not in this particular situation. Also, check the field welds to determine if the weld roots have excessive drape through. This will create small flow disturbances that can result in local plating out of contaminants along the hottest or highest heat flux side of the tube wall (fireside) downstream.