Precision welded steel tubes


Standard precision welded tubes are widely used in the engineering industry for the production of machine and equipment components.
The requirement for the precision of the tubes also determines the method of production. The tubes are supplied as cold drawn.

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Cold drawn precision welded steel tubes are meant for the mechanical engineering industry and power industry, but first and foremost for the car industry components, such as:

• Transmission / Engine
• Chassis
• Safety / Steering
• Body

Precision welded steel tubes

Dimensions of precision welded steel tubes

OUTER DIAMETER (OD)12,0 – 60,0 mm
WALL THICKNESS (WT)1,0 – 3,0 mm
EUROPEAN STANDARDSEN 10305-2
AMERICAN STANDARDSASTM A513

Steel for precision welded steel tubes

EN 10305-2E155, E195, E235, E275, E355.
ASTM A513MT1010, MT1015, MT1020, MTX1015, MTX1020, 1008, 1010, 1012, 1015, 1020, 1524.
Marking of steels according to EN standards:
E – steels for machine parts
235 – minimum yield strength in N/mm2
+N – normalized or normalized rolled (additional symbol – stage of the steel grade used for tubes)

Length of precision welded steel tubes


Types of supplied length of tubes are:
a, random 4–7 m
b, fixed 4–7 m ±500 mm
c, exact – tolerance:
• 4–5 m 0 +5 mm
• 5–7 m 0 +10 mm
• >7 m – upon agreement

Precision welded steel tubes testing

Tubes are tested with nonspecified test.

Tests:
a, cast / chemical analysis,
b, tensile test,
c, dimensional inspecti,
d, visual inspection.

Based on the agreement, there is possible customised testing. The additional tests include (mainly NDT of the weld or the entire tube surface for longitudinal defects or as proof of tightness).


Tests are performed according to:
a) eddy current leak test according to SEP 1925 or according to EN 10 246-1
b) eddy current test for longitudinal defects (the weld or the entire surface of tube) according to SEP 1917 or according to EN 10 246-3, class E3. Other tests only by agreement.

Precision welded steel tubes surface protection

The tubes are supplied with anti-corrosion protection – preservative oil. Specific method of protection or delivery of tubes without conservation on the basis of agreement.

Precision welded steel tubes ends

The ends are vertical to the longitudinal axis and are without burrs.
The ends are vertical to the longitudinal axis and are without burrs.

Special treatment of tubes ends only by agreement.

Condition of surface of precision welded steel tubes

The tube surface corresponds to the relevant standards and depends on the condition of the input steel strip, the method of tube production and the final heat treatment of the tubes. Possible states of surface quality depending on the production method is marked according to EN and ASTM A  standards as follow:

EN:

S1 (black)
S2 (picked)
S3 (cold rolled)
S4 (with agreed coating)

The outer overhang of the weld is removed.

Surface roughness value:
according to DIN – Ra ≤ 6.3 mm
according to EN – Ra ≤ 4 mm
The values do not apply to the weld area.

ASTM A:

Type 1 A.W.H.R. – “welded” from hot-rolled steel
Type 2 A.W.C.R. – “welded” from cold-rolled steel

Packaging of precision welded steel tubes


(a) tubes bound with a steel band,

Packaging by agreement:
(b) tubes wrapped in plastic sheets, burlap,
(c) tubes in wooden crates.

Structural hollow sections are supplied in packages with a circular or hexagonal outline with a weight of 300 to 3 500 kg

Packaking-STANDARD-tubes bound with a steel band
Packaking-STANDARD-tubes bound with a steel band
Packaking-STANDARD-bundle tied down by steel strap underlaid by paper
Packaking-STANDARD-bundle tied down by steel strap underlaid by paper
Packaking-STANDARD-PLUS-paper tape and polyethylene foil
Packaking-STANDARD-PLUS-paper tape and polyethylene foil
Packaking-STANDARD-PLUS-the bundle placed into a wooden box
Packaking-STANDARD-PLUS-the bundle placed into a wooden box
Packaking-PREMIUM-B-into a wooden box in which the tubes are wrapped in foil
Packaking-PREMIUM-B-into a wooden box in which the tubes are wrapped in foil
Packaking-PREMIUM-C-the bandles are wraped into and plastic foil
Packaking-PREMIUM-C-the bandles are wraped into and plastic foil
Packaking-PREMIUM-D-placing the whole shipment into foil+vacuum sealed
Packaking-PREMIUM-D-placing the whole shipment into foil+vacuum sealed

Marking of precision welded steel tubes

Tube are usually not marked.
The necessary and required data are listed on the label attached to the tube bundle:

• manufacturer
• dimension
• type
• order
• standard

Marked by a label
Marked by a label
Marked with spray either by a white or black color using InkJet
Marked with spray either by a white or black color using InkJet
Marked by stamping the data
Marked by stamping the data

DIN 50 049,
ASTM A 513

EN 10 204
a, nonspecified testing – 2.2
b, specified testing – 3.1.B or optional upon agreement


The allowed straightness of tubes with a diameter D greater than 15 mm must not exceed the value of 0.002 L for the entire length of the pipe L.
Converted to 1 m of length, it must not exceed the value of 3 mm.

Welded precision tubes are delivered in the following states of delivery (the first column shows the status according to EN, the second column shows the original state according to DIN).

Compared to the DIN standard, the EN standard distinguishes between two conditions for non-heat-treated tubes, which result from different conditions of the starting material (strip).

Cold drawn precision welded tubes:

+C BK Cold drawn / hard.
After the last cold forming no heat treatment.

+LC BKW Cold drawn / soft.
After the last heat treatment there is a subsequent slight finishing pass (cold drawing).



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