This standard is issued under the fixed designation F ; the 1 This specification is under the jurisdiction of ASTM Committee F16 on. ASTM: F – Standard Specification for Chromium/Zinc Corrosion Protective Coatings for Fasteners. 1. Scope This specification covers the basic. ASTM F/FM Standard Specification for Zinc/Aluminum Corrosion Protective Coatings for Fasteners. standard by ASTM.
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The tightening torque may vary from plain finish or other coatings, but the bolt should still function the same. Qstm also see no issues with pre-tensioning.
High Strength Bolts Coatings
Leave a Reply Cancel reply Your email address will not be published. We assumed that the properties on the bolts is not affected but the final tension might be change? T1136 Grade 3, commonly known as Dacromet.
Since we are using A bolts in our structure, we have to propose a replacement. Your first question, is it appropriate to specify ASTM F Grade 3would be best answered by an engineer familiar with the coating and the application. No other units of measurement are included in this standard. Consulting a structural engineer involved on the astj is always the best solution.
The coating process does not induce the possibility of internal hydrogen embrittlement provided that the fasteners have not been cleaned or pre-treated with an acid or phosphate. I am using A grade BC and need a smooth finish with minimal irregularities. I suppose they are similar to painting. Bandana- Asstm are no issues mixing coatings with DTI washers.
High Strength Bolts Coatings – Portland Bolt
Historical Version s – view previous versions of standard. Serge- We have very little experience with Dacromet coating. This abstract is a brief summary of the referenced standard.
Work Item s – proposed revisions of this standard. Due to hydrogen embrittlement concerns ASTM recommends against hot-dip galvanizingmechanical deposition, or electroplating with zinc or other metallic coatings on high strength bolts ultimate tensile asrm that exceed ksi.
The basecoat can contain asgm C or be non-chrome NC. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Hi, Recently we were informed that Dacromet coating is being phased out. The bolts and nuts are already coated with Dacromet and the proposal is to coat the DTI washers with Magni Hello, We have specified A Dracomet f1136 bolts for a telecommunications monopole in Canada.
A coatings engineer may choose to allow an exception in some cases, but ASTM will not officially sanction any coatings that are not approved by the F16 committee. It is required that the bolt and nut are coated by the same process, but the washer can be an alternate coating.
If so, did the tension will be higher? Parham- We cannot make specific recommendations, but I can say that painting A bolts asgm quite zstm. One year after installation the bolts are rusting. Hot-dip galvanized hex nuts are therefore tapped oversize to accommodate the thick coating, whereas F specifically states that the thread fit shall not be adversely affected. So what are the alternatives to provide corrosion resistance for A structural bolts?
The corrosion protection offered by F in those cases would be superior to nothing at all. What corrosion-resistant coatings are available for high-strength over ksi bolts?
Is fluorocarbon coating acceptable to A bolts for corrosion prevention? Normally where I see F aztm is in applications with higher strength fasteners that cannot be hot-dip galvanized, such as ASTM A heavy hex bolts. However, these fasteners are not as readily available in the marketplace as A Type 1. Protective Coatings ASTM recommends that if a protective coating is required for A asttm, one of two approved coatings is recommended.
That said, I do not know much about fluorocarbon coatings and how they are applied. Link to Active This link will always route to f11136 current Active version of the standard.
Is the coating that fragile? Although hot-dip galvanize provides high thickness level barrier protection 2 mils for substrates, it is not approved for use on axtm strength bolts because hot dip galvanize is susceptible of hydrogen embrittlement and cracking of fasteners that can result out in the field.
But there are some doubts. Since the Dacromet and Magni will be in contact with one another, Are they compatible with one another? It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application.
Since the bolts are pre-tensioned, will there be any issues with Magni with regard to pre-tensioning i. Alkaline cleaning or vapor degreasing is required along with sstm blasting to remove rust or scale. The coatings are classified into six grades Grades 1 to 6 according to the required minimum basecoat thickness, and when tested, shall conform accordingly to appearance, adhesion, corrosion resistance, blister, thread fit, and hydrogen embrittlement requirements.
They were used to in flange type splices of two ast, monopole sections. Depending on the amount of corrosive forces at work in the application, F may be sufficient, but it may not.