Tubi della curva a U dell'acciaio inossidabile dell'esportazione ASME SA213 SA688 TP316L

Export ASME SA213 SA688 TP316L Stainless Steel U Tubes finished in Pickling Annealing. Size with Outside Diameter 20mm, Wall Thickness 1.6mm, Length from 7661mm – 8050mm. Total in 882KGS.

Package in Waterproof Paper bundles and put into Plywood Cases. ASME SA688 SA213 TP316L Stainless Steel U Bend Tube Pictures as below:

Standard according to ASME SA213 SA688. Technical Requirements as below:

• Diameter of tube in the U bent portion

Nella parte piegata di un tubo a U per R = 2 × D o superiore, né il diametro maggiore né quello minore del tubo devono discostarsi dal diametro nominale prima della piegatura di oltre 10 %.

Se viene specificato un valore inferiore a 2 × D, le tolleranze possono essere maggiori, a condizione che Entropie sia d'accordo prima dell'ordine.

Lo spessore della parete del tubo nella sezione piegata a U non deve essere inferiore al valore determinato dall'equazione:

dove:

tf = wall thickness after bending, in. [mm],

T = minimum wall thickness allowed by the standard for the straight tube, R = centerline bend radius, in. [mm], and

D = nominal outside tube diameter, in. [mm].

Moreover, as per TEMA RCB §2.31 (U-Bend requirements), tube wall thining in the bends should not exceed a nominal 17% of original tube wall thickness.

• Tube leg length

Nel caso di tubi a U, la lunghezza delle gambe del tubo, misurata dal punto di tangenza della curva e della gamba del tubo fino all'estremità della gamba del tubo, non deve essere inferiore a quella specificata, ma può superare i valori specificati della quantità indicata di seguito:

Lunghezza della gamba [mm]

Up to and incl. 6000 mm : -0 / +3.2 mm Over 6000 mm to 9000 (incl) : -0 / +4.0 mm

Oltre 9000 -0 / + 4,8 mm

• Differenza di lunghezza delle gambe

The difference in lengths of the tube legs of a U tube shall not be greater than 1⁄8 in. = 3.2 mm unless otherwise specified.

• End of tube : squareness

L'estremità di un tubo può discostarsi dalla sezione quadrata per un massimo di:

• 0,25 mm per tubi fino a 5/8" [15,9 mm].
• 0,40 mm per tubi superiori a 5/8" [15,9 mm].

• Leg spacing

The leg spacing measured between the points of tangency of the bend to the legs shall not vary from the value (2 R − specified tube outside diameter) by more than 1⁄16 in.[1.5 mm] where R is the center-line bend radius.

• Bent portion curvature

La parte piegata del tubo a U deve avere una curvatura sostanzialmente uniforme e non deve superare il raggio nominale della linea centrale di 1⁄16" [1,5 mm].

• Deviation from the plane of bend

Permissible deviation from the plane of bend (Fig. 1) shall not exceed 1⁄16 in. [1.5 mm] as

misurata dai punti di tangenza.

1.   HEAT TREATMENT OF BENDING AREA

For austenitic tubes, heat treatment of the U bends is compulsory and must be carried out as per ASTM A688 / ASME SA688 § 8.6.

2.   MARKING

All tubes shall be marked with the heat number.

3.   PACKAGING

Whatever the tube material, packaging of U-bent tubes shall follow requirements of ASTM A688

§20, i.e.:

All tubing shall be packaged and blocked in such a manner as to prevent damage in ordinary handling and transportation. The boxes shall be constructed in such a manner that no nails, staples, screws, or similar fasteners are required to close and secure the box after the tubes have been placed in the box. The box shall be lined with plastic sheet or vapor barrier materials so as to prevent chloride contamination of the tube during handling, transportation, and storage.

The U-bent tubes shall be arranged in boxes so that the smaller radius bends may be removed without disturbing larger radius bends. Tubes for an item number shall be boxed together.

4.   TESTS AND INSPECTIONS

Refer to Inspection and Test Plan

The minimum requirements are:

• Eddy current test as per ASTM A1016
  • Pneumatic test either air under water test at 1000kPa (in accordance with ASTM A1016) or air differential pressure test at 1000kPa (in accordance with ASTM A1047)
  • Dimensional inspection of 100% of the tube including :
    • Diameter of tube in the U bent portion
    • Wall thickness in the U bent portion
    • Tube leg length
    • Difference of tube leg length for a U tube
    • Squareness of the tubes
    • Leg spacing : this must be measured at the end of the bent portion, in order to check that it will be possible to install a support plate just next to this bent portion
    • Bent portion curvature
    • Deviation of the plan of bend
  • Visual inspection : cleanliness, deburring and marking shall be checked on each tube