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How to know if steel bar is not substandard?

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  • angelo
    started a topic How to know if steel bar is not substandard?

    How to know if steel bar is not substandard?

    As the title says. How can u detect or know if the one you bought is not substandard?

  • rosy
    replied
    For all I know, its not in the summer time for there are lots of construction going on
    during this time. Why not get some feed backs from different hardware stores, ask
    around so you will be informed specially during this time of rainy season.

    Leave a comment:


  • odmacusi
    replied
    Hi, May I know when is the best time to buy steel bars at their lowest cost? ty!

    Leave a comment:


  • rosy
    replied
    Re: How to know if steel bar is not substandard?

    Yes horge, plus + 1 on your last post, its definitely true that most if not the majority of hardware stores do shortchange customers in terms of steel sizes or gauge thickness of tubings and pipes.

    And for the usual ordinary customers doing or DIYing projects like us, I do believe in over engineering a design and using materials above the normal standard requirement to perfectly get the right and sufficient results of strength since metals we buy tend to be sub standard or are usually under size.

    Mahirap umasa sa "pupwede na yan" syndrome just to save on costings and sacrificing on the proper strength of a design or structure.

    Well just my honest and personal opinion !!!

    Leave a comment:


  • horge
    replied
    Re: How to know if steel bar is not substandard?

    Originally posted by willyfernando View Post
    I guess it is really going to be hard for small scale users to determine the grade of their purchases. What measures can they take to at least reduce their risks given the rise in poor or sub-standard products in the market? How will they conduct their own evaluation during buying? Any pointers on what to watch out for when buying steel products?
    For small purchases...
    Checking correct weight and dimensions na lang nga... my point was that it's no
    guarantee
    . It is however a wee bit more than just a token gesture, because if a
    vendor takes the care to give you correct-size/weight sections, chances are that
    they also take some care with respect to THEIR suppliers of steel. Suppliers with
    integrity, in turn are diligent about yield-strength, on top of correct dimensions.

    There's better odds of getting good product direct from specialist steel suppliers.
    Most general-hardware stores kasi, will shortchange you (usually sa thickness of
    steel bars, plates and other sections) by exploiting the difference between SAE
    vs. Metric near-equivalents. Sa thin sections lang, yung "Ga.#" vs "mm thickness"
    switching can make all the difference if your attempt to weld burns holes in the
    steel or not.

    It also helps to over-design: whatever you THINK is sufficient, dagdagan mo pa.
    Ang kalaban mo nga lang is usually increased weight.
    Last edited by horge; 08-25-2013, 04:27 PM.

    Leave a comment:


  • willyfernando
    replied
    Re: How to know if steel bar is not substandard?

    I guess it is really going to be hard for small scale users to determine the grade of their purchases. What measures can they take to at least reduce their risks given the rise in poor or sub-standard products in the market? How will they conduct their own evaluation during buying? Any pointers on what to watch out for when buying steel products?

    Leave a comment:


  • horge
    replied
    Re: How to know if steel bar is not substandard?

    ...and that SteelAsia link from sotsab echoes what I posted earlier, that
    only destructive testing at a proper laboratory will let you KNOW for sure
    that your steel bar is not substandard. That is why the link provides a list
    of testing facilities:

    There are 3rd Party testing facilities for rebar:
    1. Philippine Geo Analytics, Inc.

    2. Metals Industry Research and Development Center

    3. Matest Laboratory Services, Inc.

    Aside from the physical appearance, you will be provided with the following information when a rebar is tested.

    Mechanical Strength - Yield Strength(YS), Tensile Strength(TS), Elongation, TS/YS Ratio and Bending
    Properties should pass minimum requirement under PNS 49 Standard.
    Mass Variation - Mass of every meter per sample should not be heavier or lighter by 6% (+/-) for all sizes.
    Physical Deformation - This pertains to the measurement (spaces and height) of lugs and ribs.
    A rebar can bear all the required marks, and tale the correct weight, but then
    contain substandard, weak steel, because a foundry added recycled junk metal
    to extend product volume. The same obviously applies to other sections such
    as smooth rods, angles, channels and plate.

    If you're using the steel to weld-fabricate a frame that will only bear light loads,
    it almost always doesn't matter much which grade of rebar you use, but where
    significant loads have to be supported (such as when rebars are used for their
    originally-intended purpose, as reinforcing bars in concrete), yield strength can
    be a deadly serious matter. Even steel from a reputable mill has to be sampled
    per batch, and subjected to destructive testing (by laboratories such as those
    listed in that link) to confirm their strength.

    The steel grades listed in the link can bear some explanation as well:

    [ASTM A1011]
    Grade 230 (Gr33) - White ... has a yield strength of 230 MPa (33,000 psi)
    Grade 275 (Gr40) - Yellow ... has a yield strength of 275 MPa (40,000 psi)
    Grade 415 (Gr60) - Green ... has a yield strength of 415 MPa (60,000 psi)
    Grade 520 (Gr75) - Orange ... has a yield strength of 520 MPa (75,000 psi)

    The unit "psi" is more familiar to laymen, so here is how you interpret the above:
    Every square inch of a Grade 230 (Gr33) rebar's cross-sectional area can support
    33,000 lbs of force (either tension or compression), before the bar permanently
    deforms. Obviously, most rebar cross-sections fail to total a single square inch, but
    then rebars are typically used in groups (reinforced concrete).

    Leave a comment:


  • rosy
    replied
    Re: How to know if steel bar is not substandard?

    Hey bro sotsab,

    Thanks for this additional link and information, we should keep this article in mind !!!!!!

    Leave a comment:


  • sotsab
    replied
    Re: How to know if steel bar is not substandard?

    read this, http://www.steelasia.com/conw.htm

    Leave a comment:


  • latest_idol
    replied
    Re: How to know if steel bar is not substandard?

    As Rosy said, Calipher is a very fast and useful tool to determine the actual size of REBARS/Pipes.

    Leave a comment:


  • rosy
    replied
    Re: How to know if steel bar is not substandard?

    Well if you are buying first hand metals at your neighborhood hardware stores, bring with you a steel measuring tape and a digital caliper so you can measure the correct dimension/s of the steel they are selling. Usually they fail in that aspect, if they say its 10 mm or 12 mm, check it out first and you will be surprised its mostly if not all under size, even gauges of GI pipes and galvanized roofing, they would alter and pass the thinner wall to thicker size wall if you are not very meticulous.

    Leave a comment:


  • aries405
    replied
    Re: How to know if steel bar is not substandard?

    since we're metric it isnt really 20 feet but rather 6 meters or 19.69 feet more or less. the 5 inch difference is a big factor when doing estimates. Ive even encountered a 19 feet steel bar. The weight is a more accurate measure of standard
    Last edited by aries405; 02-04-2013, 09:20 AM.

    Leave a comment:


  • horge
    replied
    Re: How to know if steel bar is not substandard?

    Destructive testing in a proper materials lab.
    No other way.

    Steel sections can be the correct weight and dimensions, but can have
    substandard yield-strength.

    That's why the DPWH requires it as a matter of course and pursuant to
    certain classes of building permit: samples of steel as well as of batches
    of mixed concrete) are reserved for destructive strength-testing.

    Preparing a countertop for a workspace, I was cutting some 8mm plate
    just the other week, and was shocked to find pockets of slag/impurities
    had been rolled-into the steel at the mill: My cutting disc would kick up
    a cloud of fragments, and one could see the irregularly-shaped cavity in
    the plate where the slag had been.

    I shouldn't have given-in to a friend's request that I source my steel from
    his 'friend' in Manila.
    Last edited by horge; 11-14-2012, 08:44 AM.

    Leave a comment:


  • guad
    replied
    Re: How to know if steel bar is not substandard?

    What width (nominal or actual) of steel bar do those weights assume? Is there only one width of steel bar that is commonly available?

    Leave a comment:


  • bbn
    replied
    Re: How to know if steel bar is not substandard?

    Great post bro. I've done a lot of DIY work with rebars but I honestly never bothered to check. I think I never did get any of the "asero" kind but knowing how to tell is still good to know. Also, I believe most of the hardware stores will actually tell a buyer that what they have is "undersized" but this does not necessarily mean it is low quality steel or "asero". Note DIYers though that a rebar with an actual smaller diameter than its label will surely have less strength that what it is thought to have. Most designers, especially in our country, will factor this situation into their safety factors. Best to ask your architect or civil engineer about this.

    Not every DIYer will have an appropriate weighing scale, one that can weigh down to the 0.1 kg. Bathroom scales I think have a 0.2kg resolution. What a DIYer can do is to weight several bars at the same time then dividing the reading by the number of bars to get the weight per piece. This will get one around resolution limitation, and also gives an average weight value which eliminates any normal variations. If the average is out of the ranges bro boybakal gave us then in all likelihood the bars are substandard.

    Leave a comment:

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