Also, a490 material isrequired to be magnetic particle inspected. These tc bolts are made from highstrength steel and are available in many different diameters and lengths. Metal coating malaysia, geomet, dacromet, cathodic electro. I know very little about the stuff and everything i read on the internets are from sales websites. Bolt dacromet heavy hex structural bolt astm a490 dacromet heavy hex bolt. Dacromet satisfied all of the performance criteria specified in ifi144, including paintability, coating adhesion, and rotational capacity.
Please specify whether youd prefer a pdf or a paper copy specify your mailing address, and whether youd like english or spanish. Discussion point 8 coatings beneath bolt head and washernut cont. A490 type 3 bolts are made from a corrosion resistant steel. For example, when it is compared with dichromate zinc electroplating or hot dip galvanized, the rust resistance is considerably higher. Report on the a354 grade bd highstrength steel rods on. Astm has approved coating a490 bolts with zincaluminum corrosion protective coatings per astm f16 grade 3, commercially called dacromet. They were used in flange type splices of tubular sections as well as gusset plate connections.
How to differentiate two parts having dacromet and geomet. As a last minute game change the vendor is pushing for dacromet as a finish instead of the zinc plating i specified in the drawing. Zinc plating cadmium plating dacromet coating ptfe xylan coating mechanical galvanizing geomet coating hot dip galvanizing head markings m a325m 8s pae m a490m pae. Steel dacromet bolt dacromet m30 bolt m30 m50 dacromet plated full thread hexagon bolt and nut din933. Belmetric ntlh8dac dacromet coated flange nut ntlh8dac m8x1. Astm f3125f3125m is a structural bolt specification covering inch and metric bolt grades. The dacromet coating was the best taking 4 times as long to rust spots as the yellow zinc. To achieve this, the methodology prescribed in ifi144 was applied to qualify the dacromet coating system for use with astm a490 bolts. China astm a325 alloy steel structural dacromet coating bolt for. The brand name dacromet has a patented zinc flake application where others are a powder.
Determines the mean slip coefficient of a coating applied to the faying surfaces of bolted connections under shortterm static loading each test run 7 min. This paper investigates the lubricity of the dacromet 500 coating and compares it to zinc and cadmium platings having the same film thickness. Also, a490 material is required to be magnetic particle inspected. China astm a325 alloy steel structural dacromet coating bolt for power industrial, find details about china dacromet coating bolts, dacromet hex bolts from astm a325 alloy. Brahimi, salim, 2006, qualification of dacromet for use with astm a490 high. Tension control bolts, tc bolts or twist off bolts are now the most popular choice in highstrength structural bolting and formally recognized by the aisc american institute of steel construction and the rcsc research council on structural connections as an approved installation method. A325 tension control bolts f1852, in plain or mechanically galvanized, and astm. They also have various additives and topcoats for different applications. A tension control bolts consists of 1 bolt, 1 nut and 1 washer, pre. Email your drawing jpeg, png or pdf, word with minimum 300 dpi resolution for good clarity. The dacrotized treatment provides outstanding corrosion resistance compared to other existing metal surface treatments. Astm a490 type 1 12 to 112 nominal size, 120 ksi proof strength. Oct 20, 2009 we have specified a490 dacromet coated bolts for a structural tube framing system in jersey city.
Formulated as a twocoat system and resistant to automotive fuels and fluids, magni 565 is the preferred fastener coating of leading global automotive manufacturers. Dacromet coated fasteners offers highest corrosion resistance among coated fasteners. Manufacturing of waterbased coatings and of technologies for corrosion resistant coatings under thin layer. Dacrotized is a part that has been treated with the coating dacromet. Astm a490 covers heavy hex structural bolts from 12 inch diameter through 112 inches diameter and are made of alloy steel.
Notes a490 bolts shall not be coated via hotdip zinc coating, mechanical deposition, or electroplating with zinc due to the potential for hydrogen embrittlement. Standard specification for structural bolts, alloy steel. Dacromet dacromet is a water based, metallic silver coating known for high performance. The zinc and aluminum platelets align in multiple layers forming a metallic silvergray coating. Astm a490 specification structural heavy hex bolts jf engg. All are concerned with the corrosion part of the comparative study between h. A490 covers heavy hex structural bolts tensile strength of 150 to 173 ksi and currently, astm standards do not allow hotdip galvanizing of a490 bolts for corrosion protection. Table 12 general coating condition of failed bolts. The umbrella name is zincrich coating and sometimes called cold galvanizing. A49014a standard specification for structural bolts, alloy steel, heat treated, 150 ksi minimum tensile strength withdrawn 2016. Sep 11, 20 a490 covers heavy hex structural bolts tensile strength of 150 to 173 ksi and currently, astm standards do not allow hotdip galvanizing of a490 bolts for corrosion protection.
Dacromet 500 almost identical to standard dacromet 320, this lv formulation uses ptfe in the basecoat to offer consistent torquetension characteristics without a supplemental sealer available in lc dacromet 320 hsin order to achieve thicker coating weight in an efficient manner, this lv. Citing a concern of hydrogen embrittlement, a490 only allows a type of zincaluminum coating to be used on highstrength bolts. Reference treatments for fasteners in the automotive industry. Give us a call to talk in more detail about what is the best fit for your project. Dacromet 320500 coating dacromet 320 is a an aluminiumgrey, nonelectrolytic, thin coating for antirust protection of steel, cast iron and other ferrous metal parts. Evaluation of failed nipigon river bridge west abutment bolts. Kodiak pioneered the use of brass fittings, stainless steel guide bolts and sleeves, and stainless steel pistons in. Continuous salt spray and cyclic exposure demonstrated. The coating contains zinc and aluminium flakes in a chromium binder. Dacromet 320 is a nonelectrolytic waterbased thinfilm coating for the corrosion protection of articles made from steel, cast iron, or other iron metals. A timeproven reliable coating for corrosion protection. A zincalum coating dacromet per astm f16 grade 3 has been approved for. It took a considerable amount of time including significant manual effort to.
One and a half years after installation the bolts are rusting. A timeproven reliable coating for corrosion protection high corrosion resistance for more than 35 years, dacromet has been used worldwide for high performance corrosion protection on wide variety of metallic parts metallic silver appearance coefficient of friction iso 16047. Dacromet coated a490 bolts for boeing delta iv frangible box figure 1. Dacromet is an inorganic zincaluminum flake coating brand. Tension control bolts are available in one of two different types. This coating system has gained worldwide acceptance as reliable, proven, corrosion resistant metal finishing systems which protect against road salt, humidity, solvents and other corrosive elements. The astm a490 is a specification for the bolts set by the astm international, a voluntary standards development organizations that sets technical standards for materials. Magni 565 magni 565 magni 565 is a chromefree duplex coating that combines an inorganic zincrich basecoat with an aluminumrich organic topcoat.
Is the use of ptfe coating for a490 bolts already approved by astm. This coating is astm f16f16m zinc aluminum coating, known to many within the industry as dacromet. Reference to type 2 astm a325 and type 2 a490 bolts. Available in type 1 and type 3 type 2 was withdrawn from the standard in 2002. There is a coating called dacromet that has now been approved by astm and rcsc for coating of a490 bolts. It is composed of thin zinc and aluminium plates in a chrome oxide mould. Wed like to take this opportunity to say thanks to you, our valued customers, for your continued support. There are now two different types of grades for both imperial and metric astm a490 bolts which are type 1 type 2, and type 3 as indicated by varying grade identification markings on the bolt heads. A490 specification covers only hexagon headed bolts up to 1. Dacromet coated fasteners like hex bolts,studs,nuts,washer. Astm f2833 corrosion protective fastener coatings with zinc rich base coat and. Bolted steel parts shall not be separated by gaskets and shall fit solidly together after bolts are tightened. Whether youve worked with us since our company was formed in 1974 or partnered with us more recently, its been our pleasure to work at your side to engineer highperformance coating solutions that help you prolong the life cycle of your products. Lohr structural fasteners 2355 wilson rd humble tx 77396 phone 2814466766.
Plain dacromet both a325 and a490 bolts can be painted after installation. More importantly it focuses on the effect that a coating can have on the torque tension properties of a fastener. However, one important factor is missing in the above discussion which is of course applicable to high tensile bolts of higher property class 10. X represents one location such a marking may appear. This specification contains 4 inch series bolting grades. Bimetallic capabilities one of the prime features of dacromet self drilling screws is good bimetallic corrosion resistance due to concentration of aluminum within the coating. When looking at the mechanical requirements of bolts it appears that a grade a325 and sae j429 grade 5 are identical as do the. Kodiak corrosion protection options corrosion resistance is important on all types of trailers and is a major consideration in salt water or other corrosive environments. If one bolt is having dacromet coating and another one is having geomet coating and both are having same silver colour then how to differentiate dacromet coated bolt from geomet coated bolt. One dacromet coating supplier was recommending to increase coating. Astm states that if a protective coating is required for a490 bolts, one of. A zincalum coating dacromet per astm f16 grade 3 has been approved for a490 bolts. The previous a490 specification did not have provisions for rc testing, and as. There are now two different types of grades for both imperial and metric astm a490 bolts which are type 1 type 2, and type 3 as indicated by.
Its weathering characteristics are similar to hotdip galvaninzing. Guidance on the use of dacrometcoated a490 bolts, nuts and washers. The dos and donts of painting bolted connections kenneth a. Specification for structural joints using highstrength bolts. Astm a490 bolts shall not be coated by hotdip galvanizing, mechanical deposition, or electroplating with zinc due to the potential risk of hydrogen embrittlement. These engineers want to use a490 bolts as a substitution for the same diameter a325 bolts. Coating a490 bolts with dacromet is a real advantage to engineers faced, for example, with renovating bridge connections for increased capacity, such as to the new seismic codes. Black, electro galvanize, hot dip galvanize, mechanical galvanize, ptfe, dacromet, cadmium plated coating standards en iso 4042, en iso 10684, bs en iso 1461, astm b695, xylan, astm a153. Additional testing in the form of magnetic particle inspection for longitudinal discontinuities and transverse cracks is a requirement of the a490 specification. Zinc plating cadmium plating dacromet coating ptfe xylan coating. The coating, produced by metal coatings international, is covered by astm f16 zincaluminum corrosion protective coatings for fasteners and is known by the trade name of dacromet.
Squirter dtis came out of construction concerns a recent asme paper on the recognized constructability improvements that derive from squirter. Astm has approved coating a490 bolts with zincaluminum corrosion protective coatings per astm f16 grade 3, commercially called geomet. This spec is similar to but stronger than astm a325 being that a490 is made. Astm a490 14a standard specification for structural bolts. Tc bolts including a325, a490, and galvanized tension. Guidance on the use of dacrometcoated a490 bolts, nuts and washers is available on the rcsc website. Dacromet and our various sealers and topcoats can be applied to a variety of substrates in order to provide corrosion protection to ferrous metals.
Type 2 was withdrawn from the specification in 2002. Tension creep testing tendency of a coating to undergo deformation under sustained service loading 1,000 hrs 42 days. Black, electro galvanize, hot dip galvanize, mechanical galvanize, ptfe, dacromet, cadmium plated coating standards en iso 4042, en iso 10684, bs en iso 1461, astm b695. Determines the mean slip coefficient of a coating applied to the faying surfaces of bolted connections. Product data sheet magni 565 fastener coating magni. The atmosphere was 70f with very high humidity and the presence of numerous fatty acids and oils, yarn finishes. Astm a490 bolts are intended for structural applications which means they are not only of a stronger grade but also feature shorter threaded lengths of the bolt to avoid interference with the joint. Improving understanding of the performance of a325 and a490 steel bolts.