Fired Crude Heater - Hydrostatic Test

[zayed78]

Hi all,

Fired crude heater in service for 30 years . it is a cabin heater with horizontal tube coils. The convection contains twelve (12) original finned carbon steel tubes (A106 Gr B) and four (4) 5Cr-0.5 Mo (A335 P5) alloy tubes. The radiant contains 36 tubes - 5 Cr-0.5 Mo materials. Decision made to replace all convection tubes by new finned carbon steel also 02 of radiant section ( mechanical damaged and low UT thickness) by new 5 Cr-0.5 Mo materials pipe.

My question here is Hydrostatic Test required or not?

Note that we did 100 % radiography (PAUT) for all welds ( for new tubing) and random for old welds.

 

[GD2]

OP,
You are not required by the Code (ASME, if you follow ASME codes and Standards) to do a mandatory pressure test. ASME PCC-2 is applicable in this case.
You need to consider risk-factors going for a pressure test. One of these is a chance of brittle fracture as I am sure metallurgy of few tubes (specially A106 B) may have changed over time.
You must have also done NDE for surface flaws (LT, MT etc) in addition to PAUT which is used for volumetric flaws.

GDD
Canada

 

[georgeverghese]

"Decision made to replace all convection tubes by new finned carbon steel...."

So what about the low alloy high temp CS bare tube section in the existing convection bank ? This lower bare tube section is called the shield bank and is used to minimise the radiant heat exposure of the upper finned tube section.

 

[0707]

For your tubes replacement you should follow API530,IMO after the NDE forcasted you should perform hidrotest.

 

[Dhurjati Sen]

Is the heater plug type? An affirmative would answer your question.
If it is not a plug type, still does it have flanges? If yes, same answer.
The Company does have an operation and maintenance code.
Even the heater OEM must have given repair procedures.
What do these say?

DHURJATI SEN
Kolkata, India

 

[Krausen]

Typically you're design conditions on heater tubes are fairly low pressure, high temperature. Performing a hydrotest to API530 (1.5 x DP x Stress Ratio) is usually pretty feasible, unless your coils have older/existing plug header returns (instead of typical 180deg return bend fittings). The older plug header returns are notorious leakers that are difficult to bring to full hydro pressure.

If you have 180deg return bend fittings everywhere, just hydro everything to API530 & sleep soundly at night.