Steam Blowing Procedure

[moe]

Dears,
as we approached the Pre-commissioning phase in a newly constructed Petrochemical Complex, I would like to know if anyone have the proper procedure for steam blowing for HS,MS & LS line ?
also, the criteria of using the target plates during the blowing period ?
thanks,
your inputs would be highly appreciated.

[Imran.Idris]

Luckily we are just done with steam blowing of HS, MS, and LS at our fertilizer complex. The basics that were followed during steam blowing are given below

Steam blowing utilizes kinetic energy of steam flow. Since blowing and cool down of the pipe concerned are repeated during steam blowing, rust, weld slag or spatter become liable to peel off the pipe surface due to the repetition of expansion and contraction of the pipe. This produces a more effective blow-out which would be impossible by usage of kinetic energy alone. The effectiveness depends on the steam velocity, the change of temperature in time and the number of blows.
Between the blows there should be a cool down period of at least 180 minutes for non insulated pipes and 480 minutes for insulated pipes.
A steam system feeding a turbine is considered to be acceptably clean when the target plate has less than a predetermined number of impact pock marks as below indicated.
The following general rules shall apply to assess steam blowing effectiveness:
a. Steam flow required can be estimated by means of the following formula:
M1 = 1.2* M2 ((P1* (273+T2)) / (P2 * (273+T1)))^0.5
Where M1 = Steam mass flow rate during blowing, (Mt /hr)
M2 = Max steam mass flow rate during operation (Mt /hr)
P1 = Steam pressure during blowing close to vent pipe (ate)
P2 = Steam pressure during operation (ate)
T1 = Steam temperature during blowing (°C)
T2 = Steam temperature during operation (°C)
b. In case the above formula cannot be applied due to operational constrains then steam blowing is considered effective if the steam blowing velocity is equal or higher than steam velocity during operation.
c. In case of operation steam temperature cannot be reached then a reduction of 30% is acceptable as long as steam is superheated.
d. There should be not more than one total particle count less than 0.6 mm per square centimetre on the target plate surface.
e. There shall be no evidence of embedded material (weld splatter, sand, etc.). Target plates shall not show individual rough impressions.
f. The blow down shall not be carried out for more than 15 minutes and not less than 10 minutes duration.
g. The first 3 – 4 blows shall be made without target plate.
h. Steam blowing is considered acceptable when two consecutive target plates are showing same results as per above criteria.

I hope you get your answer

Regards,

Imran

[moe]

Thanks alot Mr.Imran, that's the answer that I was looking for, very rich & informative answer, thank you once again.

[Imran.Idris]

You are most welcome....