ASTM A688/A688M-18 Standard Specification for Seamless and Welded Austenitic Stainless Steel Feedwater Heater Tubes
This specification covers standard requirements for welded austenitic stainless steel feedforward heater tubes including those bent, if specified, into the form of U-tubes for application in tubular feed-water heaters. All finished straight tubing or straight tubing ready for U-bending shall be furnished in the solution-annealed condition. The steel shall conform to the required chemical composition for carbon, phosphorus, chromium, molybdenum, nitrogen, and copper. The material shall also conform to tensile properties such as tensile strength, yield strength, and elongation. The steel shall undergo mechanical tests such as tension test, hardness test, reverse bend test, flattening test, flange test, pressure test, hydrostatic test, and air underwater test. Nondestructive test (electric test) shall be performed and corrosion resisting properties shall be determined for each sample tube.
U-Bend Tube are widely used in Heat Exchanger Systems. Heat-Exchanger Equipment on the basis of Seamless Stainless U-Tubes and Welded Stainless U bend Tube is essential in strategically important and critical felds---Nuclear And Petrochemical Machine Building.
The U-Bend Tube Comply With The Following Standards:
1. ASTM A688/ASME SA688
2. ASTM A803/ASME SA803
3. ASTM A556/ASME SA556
Steel Grade
Ferrite | Austenite | Duplex | Super Duplex | Ni-Alloys | Titanium |
TP410 | TP304/304L | S31803 | S32750 | N06600 | Gr.2 |
TP405 | TP316/316L | S32205 | S32760 | N08020 | |
S44400 | TP316Ti | S32304 |
| N00880 | |
S44660 | TP317/317L |
|
| N08825 | |
TP430 | TP321 |
|
| N08904 | |
| TP347 |
|
|
|
Bending Radius: From 1.5*OD(Outside Diameter) To 1500mm When Ordering Tubes With Radius less or equal to 1.5*OD, It Is Necessary To Agree Precision Of Geometrics.
Straight Tubes Maximum Length: (Before Bending): 35000 mm.
Leg Length: Min 1 Meter, Max. 16500 mm (For Max R=1500mm)
Note: Other Size Are Available Upon Agreement.
Heat Treatment: Stress Relieved After U-Bending (Bending Area Plus 300MM For Each Leg).
Hydrostatic Test After U Bending: Maximum Test Pressure 600 Bar, Soaking 10 Sec. With Dematerialized Water. Compressed Air Cleaning After Hydro-Test.
Packaging: In Strong Transport-Worthy Pre-fumigated wooden boxes of corresponding dimensions for each tube Length, Radius, Diameter, According To PO requirements as well as wrapped In polyethylene films With soft plastic caps on both end of Tube.
Some of the quality tests carried out by us includes:
| Corrosion Test | Conducted only when specially requested by the client |
| Chemical Analysis | Test done as per required quality standards |
| Destructive / Mechanical Testing | Tensile | Hardness | Flattening | Flare | Flange |
| Reverse-bend and Re. flat tests | Carried out in full compliance with relevant standards & ASTM A-450 and A-530 norms, which ensures trouble-free expansion, welding & use at customers end |
| Eddy Current Testing | Done to detect homogeneities in subsurface by using Digital Flaw-mark Testing System |
| Hydrostatic Testing | 100% Hydrostatic Testing carried out according to ASTM-A 450 norms for checking tube leakage, and biggest pressure we can support 20Mpa/7s . |
| Air Under Pressure Test | To check any evidence of air leakage |
| Visual Inspection | After passivation, every single length of tubes & pipes is subjected to thorough visual inspection by trained staff for detecting surface flaws & other imperfections |
