Carbon Steel Pipe A53/A106 Gr. B, A333 Gr. 6

ASTM A53 CHEMICAL COMPOSITION

There are two ASTM A53 pipes grades, i.e. grade A and B. The two grades feature slight differences in terms of chemical composition (mainly Carbon and Manganese content) and mechanical properties – as shown in the pipe grades charts below:

Maximum values in %	Type S (Seamless)		Type E (ERW)		Type F (Furnace Weld)
A53 Pipe Grade–>	Grade A	Grade B	Grade A	Grade B	Grade A
Carbon	0.25	0.3	0.25	0.3	0.3
Manganese	0.95	1.2	0.95	1.2	1.2
Phosphorous	0.05	0.05	0.05	0.05	0.05
Sulfur	0.045	0.045	0.045	0.045	0.045
Copper	0.4	0.4	0.4	0.4	0.4
Nickel	0.4	0.4	0.4	0.4	0.4
Chromium	0.4	0.4	0.4	0.4	0.4
Molybdenum	0.15	0.15	0.15	0.15	0.15
Vanadium	0.08	0.08	0.08	0.08	0.08

A53 Gr. A/B PIPE MECHANICAL PROPERTIES

Seamless and ERW	A53 Grade A	A53 Grade B
Tensile Strength, min, psi	48,000	60,000
Yield Strength	30,000	35,000

A53 PIPE PHYSICAL PROPERTIES

Density at 20 °C Kg/dm³	Modulus of elasticity kN/mm² at				Thermal conductivity at 20 C° W/m K	Spec. thermal capacity at 20 C° J/kg K	Spec. electrical resistivity at 20 °C Ω mm²/m
	20 C°	300 C°	400 C°	450 C°
7,85	210	192	184	179	51	461	0,20

HOT FORMING AND HEAT TREATMENT

Hot forming		Heat treatment
Temperature °C	Type of cooling	Normalizing 1)	Stress-relieving anneal 2)	Type of cooling
1100 – 950	Air	890 – 950 °C	600 – 650 °C	Air

Notes: 
1)   Normalizing: Holding time 1 minute per mm plate thickness, a minimum of 30 minutes
2)   Stress-relieving anneal: Holding time 1-2 minutes per mm plate thickness, minimum of 30 minutes

PIPE END TYPES

• Pipe schedule below 0.500 inches and schedule STD / XS pipes: plain or beveled ends
• Pipe schedule above 0.500 inches and schedule XXS: Squared cut plain ends

If pipes are supplied with threaded ends, protection for threads is mandatory for pipes above 4 inches.

MARKING

Each length of pipe (or bundle for smaller diameters) shall have the following markings applied:

• Manufacturer name
• A53 type (S, E, F)
• Diameter and schedule (from 10 to 160 and XXS)
• Designation “ASTM A53”
• Pipe length
• Heat number

It is frequent to find pipes on the market pipes that comply, at the same time, with multiple standards: A53, A106, API 5L Gr. B. Such compliance is shown as a mark on the pipe itself.

GALVANIZED PIPE ASTM A53

What means galvanized pipe?

Galvanized pipes are steel pipes that have been hot-dipped in a protective zinc coating to prevent corrosion and rust (the process is called “hot-dip galvanization”). Galvanized pipes were introduced in the sixties as an alternative to lead pipes for water transmission and distribution. After that, they have been used also for sewerage applications, firefighting, and general plumbing systems.

During the galvanization process, the zinc coating applies both to the outside and the inside of the pipe. The standard zinc coating is between 1.6 and 1.8 oz per square foot.

Galvanized pipes show long-lasting durability, improved resistance to corrosion compared to standard black steel, and are available at a relatively cheap price (and good toughness) compared to alternative metals (the price of galvanized pipe vs copper maybe, to give a general indication, 6 times lower per metric ton).

As a rule of thumb, the galvanized price is between 40 and 50% higher than the price of black carbon pipes (the application of a zinc coating requires the transportation of the bare pipe to the galvanization plant, the application of zinc raw material on the pipe and other finishing activities).

On the other side, galvanized pipes are heavy, difficult to repair and tend to develop blockages over the course of time (the internal part of the pipe is subject to corrosion, and it’s not infrequent to find completely rusted galvanized pipes few years after their installation).

ASTM A123, ASTM A153, and ASTM A53

First and foremost, there is a difference between ASTM A53 and ASTM A153. Companies specialized in pipes galvanization are familiar with the ASTM A153 specification (“Standard Specification for Zinc Coating Hot-Dip) on Iron and Steel Hardware”.

The section 17 of the more general ASTM A53 specification, sets requirements for galvanized pipe, i.e. it requires the pipe to be hot-dip galvanized with a zinc grade in accordance with the B6 specification (Standard Specification for Zinc ) and specify the minimum weight per unit area of the coating.

The ASTM A53 specification does not set requirements related to the finishing, the appearance, or the adherence of the galvanized coating that is instead well defined in the ASTM A123 specification (Standard Specification for Zinc, Hot-Dip Galvanized, Coatings on Iron and Steel Product).

Further, the weight per unit area of the coating defined in the ASTM A53 specification corresponds to the minimum coating thickness requirements of ASTM A123. Therefore, the ASTM A123 specification is more stringent than ASTM A53 with reference to the galvanized coating and whenever a pipe is galvanized according to ASTM A123, it meets the requirements of section 17 of ASTM A53 as well.

Conclusion: when a buyer requires galvanized pipes according to A53, a galvanization process in line with ASTM A123 meets the looser galvanization requirements set by ASTM A53.A