SAE J-525B
NFPA STD T3.15.67.1
ANSI B93.4-1969


This specification covers cold worked and annealed electric resistance welded low carbon steel pressure tubing with outside diameter 3/8 inch to 2-1/2 inch, inclusive, for use as hydraulic lines for industrial equipment or other applications requiring flaring and bending.

CHEMICAL COMPOSITION (percentage by weight)

Carbon 0.18 maximum
Manganese 0.30 – 0.60
Phosphorus 0.040 maximum
Sulphur 0.050 maximum


The tubing shall conform to the following requirements:

Tensile Strength 45,000 psi minimum
Yield 25,000 minimum
Elongation in 2 inch 35 percent* minimum
Rockwell Hardness B65 maximum

* For tubes with OD of 3/8 inch and/or wall thickness of 0.035, a minimum elongation of 30 percent is permitted.

FLATTENING TEST — A section at least three inches in length shall be taken from every 1500 feet or less of finished tubing and shall be flattened between parallel plates to three times the wall thickness of the tube. The weld shall be placed at a point of 90 degrees from the direction of applied force. Any cracking or flaws revealed by this test shall be cause for rejection. Superficial ruptures resulting from minor surface imperfections shall not be cause for rejection.

REVERSE FLATTENING TEST — A section at least four inches in length shall be taken from every 1500 feet or less of finished tubing and split longitudinally 90 degrees on each side of the weld and the sample opened and flattened. There shall be no evidence of cracks or lack of penetration or overlaps resulting from flash removal in the weld.


EXPANSION TEST — A suitable specimen shall be taken from each 1500 feet or less of tubing and subjected to an expansion over a plug. The outside diameter must be expanded 25 percent throughout a length equal to the outside diameter of the tubing or one inch, whichever is greater. There shall be no evidence of cracking in this test.

PRESSURE OR ELECtrICAL TEST — Tubing supplied under this specification shall have been hydrostatically tested at a fiber stress of 20,000 psi or at an actual pressure of 5,000 psi, whichever is less, based on the applicable minimum wall, or tested by use of a nondestructive electrical test approved by purchaser.


When tubing is specified by outside diameter and inside diameter, the tolerances shown in the table shall apply.

Nominal Outside Diameter, Inches
Over 3/8 to 5/8 inclusive
Over 5/8 to 2 inclusive
Over 2 to 2-1/2 inclusive

When tubing is specified by the outside diameter (or the inside diameter) and the nominal wall thickness, the tolerances for the specified diameter shall apply and the wall thickness shall not vary more than plus or minus 10 percent.


MANUFACTURE — The tubing shall be normalized and followed by a cold working operation. The cold working shall result in minimum reduction of areas of 15 percent of which at least 8 percent shall be reduction of wall thickness. After cold working, the tubing shall be annealed in such a manner that the resultant product will meet all requirements of this specification.