Holding Time for Hydro Test or Pressure Test

Dear sir,

I know that holding time for piping is 10 minutes as per the B 31.3 para. 345.2.2 (a) while conducting hydro test but could you explain me some one about the pressure vessel what is the holding time because I couldn't find any information from Sec VIII Div 1, UG-99.

Thank you,

Ilangkumaran