pressure increase in steam header pipe

[Ayed alharthi]

dear gentelmen;
in the power plant we have power generation and water production. we have4 HRSG producing steam and this steam is using for 9 desslination units. the steam header is haveing pressure and temp. of 10.6Kg/cm2 and 186dgree celisus.
due to any problem causing of reducing the steam consumption for desalination units,the pressure in the steam header will increase.
so i am looking for how can calculate the amount pressure increase.

regards...........

[gateaux_boy]

This mean class 150, pressure can be raised to 13 barg @200 C