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Standards & Welding Code

 

ASTM A955/A955M Stainless Steel Standard

Standard Specification for Deformed and Plain Stainless-Steel Bars for Concrete Reinforcement

The ASTM A955/A955M standard specification is the accepted norm for the mill manufacture of stainless steel reinforcement. The standard has an international perspective though it is more prevalent in North America. A955 key points.

The main features of interest to stakeholders include : 

  1. Inclusion of two stainless steel classifications – duplex and austenitic 

  2. A range of stainless steel chemical formulations 

  3. Mechanical and physical property requirements, and grade strengths available

  4. Dimensional bar profiles, bar sizes, and bend diameters 

  5. Reference to surface quality and finish

  6. A note that pickling is mandatory which improves the corrosion resistance

  7. Grade structure (strengths) are equivalent to those of conventional black steel

  8. Procedures for mandatory corrosion testing 

  9. A supplementary requirement pertaining to magnetic permeability

  10. Requirements for adding new alloys 

It is worth noting that A955 reflects the changing needs of users. As such the standard is frequently updated. A copy of the Standard can be obtained through ASTM.

AASHTO M 334M/M 334 Standard

Standard Specification for Uncoated, Corrosion-Resistant, Deformed and Plain Chromium Alloyed, Billet-Steel Bars for Concrete Reinforcement and Dowels 

The AASHTO M 334 standard specification covers uncoated corrosion resistant steel reinforcement bars and dowels which includes stainless steel. Black carbon bar is not included. The content pertaining to stainless steel bars follows that of ASTM A955 though the group of alloys has not been adjusted to reflect A955. M 334M key points.

The main features of interest in this standard include : 

  1. It covers both A955 and A1035 (MMFX) material 

  2. The standard notes a possible limitation of coiled bar size based on equipment capacity

  3. It provides guidance on the factors to be considered in specifying the degree of corrosion resistance 

  4. It includes three yield levels or grades which are similar to conventional black carbon steel

  5. It lists the appropriate AWS welding code to be applied for the types of steel in the standard

  6. The standard is in SI and inch-pound units; values are not necessarily equivalent

  7. Of interest is the “Terminology” section which defines relevant terms such as corrosion-resistant, uncoated corrosion resistant reinforcement, deformed bar, etc.

  8. M 334 includes the chemical composition for a range of types of stainless steel reinforcement, deformation and dimensional requirements for various bar sizes in SI and inch-pound units, strength properties, bending requirements, and surface finish requirements

  9. It provides guidance on optional corrosion resistant test methods which can be used to evaluate the sensitivity of stainless steels to specific types of attack, and test methods to evaluate the comparative corrosion resistance of various steel bars.

A copy of the Standard can be obtained through AASHTO’s website.

AASHTO LFRD

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British Standard BS 6744:2016 

Stainless Steel Bars - Reinforcement of Concrete - Requirements and Test Methods 

British Standard BS 6744 is more than a mill manufacturing standard. It also outlines a prescriptive-based guidance on the durability of reinforced concrete and a corrosion resistance test method. The standard weighs in on performance durability design models but does not provide advice. BS 6744 has positioned itself as the preferred choice of stainless steel standard in the UK and internationally. Main features of BS 6744. 

The main features of interest to stakeholders include : 

  1. Metric bar sizes, area, mass by steel designation, and bend diameters

  2. Stainless steels and their chemical composition classified for their properties of :

  1. low magnetic permeability,  

  2. corrosion resistance to chloride ingress in concrete

  3. corrosion resistance where the steel is exposed

  1. Two stainless steel classifications – duplex and austenitic 

  2. Reference to surface quality and finish

  3. Surface and rib geometry

  4. Mechanical and physical property requirements, strengths and testing procedures

  5. A test method for determining the corrosion resistance of stainless steel reinforcing in chloride contaminated concrete

  6. Mandatory testing for detrimental metallurgical phases (duplex types) and intergranular corrosion (austenitic and duplex types)

  7. A prescriptive-based guidance on the durability of reinforced concrete indicating the type of stainless for given exposure conditions

  8. The standard discusses performance durability design models such as the fib Model Code; however, citing the need for more research it does not provide advice on these models

  9. Guidance on magnetic properties, coefficients of thermal expansion and welding

A copy of the Standard can be obtained through the British Standards Institution.

Stainless Reinforcement Fabrication Standard

ANSI / CRSI – IPG4.1 : 2016  

Standard Practice for Stainless Steel Reinforcing Bar Fabrication Facilities

IPG4.1 outlines the appropriate fabrication methods and procedures to fabricate stainless steel reinforcement in a manner that conforms to the standard accepted practices while ensuring that contamination of the steel with carbon steel is eliminated. Key fabrication methods.

Putting aside quality assurance responsibilities and personnel training components of the standard, those parts of IPG4.1 dealing with the fabrication side of the business include :

  1. A material “accept/reject” criteria and treatment of non-conformities

  2. Frequency of plant wide inspection for carbon contamination

  3. Procedures regarding the quality of material upon receipt

  4. Methods, procedures and special protection materials and devices used throughout the operation in handling and storing the material

  5. Special procedures and protection systems for storing material outdoors

  6. Methods, procedures and special protection materials and devices used throughout the plant in the bending and shearing operations

  7. Special procedures and protection systems for shipping material 

A copy of the Standard can be obtained through the CRSI.


Structural Welding Code – Stainless Steel

AWS D1.6

This American Welding Society (AWS) code establishes the requirements for welding stainless steel using the gas metal, shielded metal, flux cored, and submerged arc welding processes, including stud welding. The code covers design, fabrication, qualification and prequalification of procedures welding personnel qualification, and inspection. It is ANSI approved. The code is available online.

Different Stainless Steel Standard Designation Names