|U-bent Tubes for heat exchanger
|| Leg Length 12.5m (41')~27m（max.dev.Length 88’)
||ASTM A213/ASME SA213
||TP304/304L, TP304H, TP316/316L, TP347/347H, TP316Ti, TP321/321H, TP310S
||Seamless Ferritic and Austenitic Stainless Steel U-bent Tubes
||TP304, TP304L, TP316, TP316L…
|| Welded Stainless Steel U-bent Tubes
||SAF2205/UNS S31803/32205, SAF2507/UNS S32750…
||Duplex Stainless Steel U-bent Tubes
||Monel400, Inconel600, 625, Incoloy800/800H, 825…
|| Seamless Nickel Alloy U-bent Tubes
||TP405, TP409, TP410, TP430
||Ferritic and Martensitic Stainless Steel Seamless U-bent Tubes
||321, 347, 310,UNS-S32760, S31803, S31500
| Seamless and Welded Stainless Steel Low Pressure Feed Water Heater(FWH) U-bent Tubes
|| Leg Length 12.5m (41’)-27m（max.dev.Length 88’)
||304/304L/304H(1.4301/1.4306/1.4948); 316/316L(1.4401/1.4404);316Ti(1.4571); 321(1.4541);309S(1.4833);310S(1.4845); 317L(1.4438);321H(1.4878);347H(1.4550); 2205(1.4462) ; S31803,2507
|| Low Pressure Feed Water Heater of Thermal Power
'U' bending is done by cold working process.
'U' bending is done to the required radius as per customer drawings.
The bend portion and six inch leg is stress relieved by resistance heating.
Inert gas (Argon) is passed through it at the required flow rate to avoid oxidation in ID.
The radius is checked for its OD and wall thinning with the recommended specification. The physical properties and microstructure is checked at three different position.
Visual inspection for waviness and cracks is done with Dye Penetrant Test.
Each tube is then hydro tested at the recommended pressure to check for leakage.
Cotton ball test is done to check the ID cleanliness of the tube. Thereafter pickled, dried, marked and packed.
All procedure is strictly followed as per TEMA "C" and ASTM A-688.
Maximum lengths of 27000mm can be supplied on request
Bending radius: Maximum 1000 mm
The basic Testing and processing:
1. High Pressure Hydrostatic Test:Minimum:10 Mpa-25Mpa.
2. Air Under Water Test After Bending
3. U Tubes Wall Thickness Test
4. Eddy Current Test before U bend Formed
5. Ultrasonic Test before U bend Formed
6. Heat treatment to stress relieved
7. Ball passing test
Heat treatment:Stress relive annealing of U-tubes after bending
Dimensional tolerances U-tubes acc. to TEMA R.C.B.
Length of straight part -0/+5 mm
Flattening (also called “ovality”) at the bend shall not exceed 10% of the nominal tube outside diameter.
Wall thickness in bending part acc. to TEMA RCB 2.31
Minimum tube wall thickness in the bend part (T min)
T(min) ≥ (SW × (2×R + D))/( 2× (R+D)
where: SW is smallest wall thickness
D Nominal outside diameter
Radius tolerance 1) for R 100 mm +/- 3 mm
2) for R ≥ 100 mm +/- 5 mm
Straightness tolerance max. 1,5 mm per 1 m
U-Tube ends: plain, vertically cut to the tube axis
Repairs by welding: prohibited
Surface condition Finished U-tubes shall be free of scale, without scratches after bending,
Coating :Passivation and oiled, Black paint or varnish
Packing:Plastic plugs in both ends, bundles of max. 3,000kg with several steel strips, Two tags on each bundle, Wrapped in waterproof paper packed in wooden case
USAGE: Heat Exchanger; Steam Boiler;Hot-Water Boiler; Medium temperature Boiler serve ; oil and gas transportation,low-temperature serve; Shipbuilding ect.