Please see reply from the TWI expert Geoff on this subject topic.
Rgds
Sayee
-----------------
Sayee
There are some concerns in Europe about exposure to high levels of
electromagnetic fields (EMF) and the EU has published a Directive (EU
law) that will require employers to take precautions to limit workers
exposure. This Directive 2004/40/EC was do to come into force in 2008
but has been postponed until 2012. It will affect all industries.
It is the frequenct components of the welding current, due to AC or
ripple, that are of concern. For ESW and SAW the frequency components
are low ie 50/60 Hz and harmonics ( 150/180Hz, 250/300Hz etc.) The
limit value at 50 Hz is currently 0.5mT. Walking over a straight cable
at 2000A is unlikely to exceed the limit values but if the cable is
coiled the EMF will be much greater. Very close to the cable the field
may exceed the limit values, but the field falls off very quickly with
distance.
These limit values come from ICNIRP guidance see,
http://www.icnirp.de/documents/emfgdl.pdf
At low frequencies the effect is neurological and at very high EMF
levels you may see flashing lights, feel sick and get a metallic taste
in your mouth. However, there is no conclusive evidence of any long term
effects. It is only fields above 100kHz (which have a heating effect on
body tissue) that may cause problems with repeated exposure.
TWI has extensive experience in EMF assessments for member companies,
see http://www.twi.co.uk/content/c1442.html
Regards
Geoff.
----------------------------
From: "Bathula Raghuram (Mumbai - PIPING)" <R.Bathula@ticb.com>
Date: 22 July 2010 05:44:54 GMT+01:00
To: "'materials-welding@googlegroups.com'"
<materials-welding@googlegroups.com>
Subject: [MW:6069] Safety Aspects while welding at high currents
Reply-To: materials-welding@googlegroups.com
Attached AWS fact sheet on safety (EMF)
It states "Most studies to date indicate that there is no evidence of
significant health problems from EMF" however it also specified some
precautionary guidelines.
------------------------------------------------------------------------
--------
From: materials-welding@googlegroups.com
[mailto:materials-welding@googlegroups.com] On Behalf Of PREM
SHANKARDUTT NAUTIYAL
Sent: Wednesday, July 21, 2010 10:24 PM
To: materials-welding@googlegroups.com
Subject: [MW:0] Safety Aspects while welding at high currents
Dear Friends
We use very high welding currents for ESW or Tandem SAW.
Currents go upto 2000A while ESW.
Now i have observed that the welding cables lying on shopfloor form
coils and generate a magnetic field when welding is on. I have checked
the magnetic field personally with Gaussmeter while ESW.
Now many people in shopfloor unknowingly walk over these cables while
welding is ON at such high currents.
My question is that whether this magnetic field will have any effect on
the health of people walking over it ???
I have identified this as a Hazard as per OHSAS, and would like to know
the Aspect and Impact.
Whether any study about safety of people has been carried out around the
globe considering welding at such high currents ??
Expert comments are required please.
Regards
Prem Nautiyal
PREM S NAUTIYAL
CELL : 9820313278
TWI Ltd
Registered Number: 3859442 England
Registered Office: Granta Park, Great Abington, Cambridge, CB21 6AL, UK
_______________________________________________________________________
The information in this e-mail is confidential, and may be legally
privileged. It is intended only for the person(s) specified in the
above address. Access to this e-mail by anyone else is unauthorised,
and any disclosure, copying, distribution or other use of this e-mail
is prohibited and may be unlawful. We will not under any circumstances
have any responsibility or liability arising out of or in connection
with any unauthorised use of this e-mail. Please inform us if this
message has gone astray before deleting it.
Please note that all e-mail is monitored.
When sending e-mails to TWI, please help us by including your name,
company, and details in your e-mail signature.
Seeking Technical Information? Industrial Members can access data as
JoinIT registrants on http://www.twi.co.uk
_______________________________________________________________________
--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding-unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
No comments:
Post a Comment