Stainless Steel Seamles Pipe ASME SA312 TP310 , Tube Coil for Fired Heater Convection and Radiant Section

Stainless Steel Seamles Pipe ASME SA312 TP310 , Tube Coil for Fired Heater Convection and Radiant Section.

Part 1: Bare Tube for Tube coil ( Covection Tube & Radiant Tube )

1.Tube-wall thickness for coils shall be determined in accordance with API 530, in which the practical limit to
minimum thickness for new tubes is specified. For materials not included, tube-wall thickness shall be determined in
accordance with API 530 using stress values mutually agreed upon between purchaser and supplier.

2. Unless otherwise agreed between the purchaser and supplier, calculations made to determine tube-wall
thickness for coils shall include considerations for erosion and corrosion allowances for the various coil materials. The
following corrosion allowances shall be used as a minimum:
a) carbon steel through C- 1 / 2 Mo: 3 mm (0.125 in.);
b) low alloys through 9Cr-1Mo: 2 mm (0.080 in.);
c) above 9Cr-1Mo through austenitic steels: 1 mm (0.040 in.).
NOTE For erosive services, the purchaser may consider adding additional allowance as required. This allowance is intended to
be treated in the calculations as “corrosion allowance”.

3. Maximum tube metal temperature shall be determined in accordance with API 530. The tube-metal temperature
allowance shall be at least 15 °C (25 °F).

4. All tubes shall be seamless. Tubes shall not be circumferentially welded to obtain the required tube length,
unless approved by the purchaser, in which case the location of welds shall be agreed by purchaser. Electric
resistance welding shall not be used for intermediate welds. Tubes furnished to an average wall thickness shall be in
accordance with tolerances that provide the required minimum wall thickness is provided.

5. Tubes, if projected into header box housings, shall extend at least 150 mm (6 in.), in the cold position, beyond
the face of the end-tube sheet, of which 100 mm (4 in.) shall be bare.

6.Tube size shall be selected in accordance with sizes as indicated in Table 5.
NOTE 1 Other tube sizes should be used only if warranted by special process considerations.
NOTE 2 Pipes and tubes have different specification criteria and manufacturing tolerances. The intent of this clause is to keep
the outside diameters consistent with nominal pipe size specifications.

7. If the shield and radiant tubes are in the same service, the shield tubes shall be of the same material as the
connecting radiant tubes.

Part 2: Extended Surface( Studded Tube ,  Solid Fin Tube ) :
1. The purchaser shall specify or agree on the type of extended surface used in convection sections:
a) finned — where helically wound fins are high frequency continuously welded to the tube, or;
b) studded — where each stud is attached to the tube by arc-resistance welding.

2. Where finned extended surface finning is used; the purchaser shall specify or agree on the use of solid or
segmented (serrated) fins.
NOTE Other extended surface designs may be allowed with purchaser acceptance.

3.  Metallurgy for the extended surface shall be selected on the basis of maximum calculated tip temperature
as listed in Table 2.