Ian I presume that you are contemplating to use virgin HP micro alloyed tube of Chinese manufacture for your reformer furnace. For this H Scan application does not arise at the manufacturing stage. H scan is a new variation in recent years mostly applicable for used reformer tube life assessment - combining a host of N.D.T techniques (as no single technicque is fool proof even today) - + a computerized prediction methodology for failure rate assessment - to increase or improve probability with more reliability in prediction assessment. H Scan - to my mind - comes for diagnostic prediction only after you operate the tubes for a period of > 30,000 hrs . ET for both virgin manufactured testing as well for used eformer tubes is still not a totally proven method - i guess - from reliability of prediction. Centri cast tubes, as you are doubtless aware - are coarse grained and hence ET will have difficulties in assessment unless great efforts are made to standardize and accurately predict with pre-existing defect detection capability. ET of a virgin refromer tube requires very high precision calibration standardization which i guess very few inspection companis and manufacturers of reformer tubes have capability (world wide). I am not sure how many companies have successfully evolved such high precision defect detection capability for reformer tube scanning. Plese note that ET scan of heat excanger tube is totally different from a centri-cast reformer tube scanning. For a virgin manufactured tubes ordered and specified to P.O. terms from well established centrifugal reformer tube manufactured locations should have full testing and inspection code stringency including micro-analysis / metallurgical analysis of each batch of casting. This would ensure HP micro alloyred tubes had undergone all testing needs specified and agreed between client and manufacturer. If you are very particular, you should assure yourself that the manufactured HP micro alloy tube from a Chinese source had undergone all the necessary short term 1000 hr / 10,000 hr stress-rupture tests to suit your design criteria with approved third party inspection of the same at the manufactured site or their approved laboratories. This should be done at the P.O and manufacturing stage before shifpment of the lot is made from China. H Scan comes very late only after > 30,000 hr operational service life - i guess - for a new tube to be placed and commissioned in a furnace. Trust this helps you C.V.Srinivasan Nishi Engineers Pvt Ltd India July 19, 2006 E-mail: nishi@vsnl.com >Following the failure of one of our HP Modified tubes in the >Hydrogen Reformer, it was decided to retube the entire >Foster Wheeler designed furnace using Micro Alloyed tubes. >These tubes were manufactured in China. >I am trying to decide if to use Eddy Current or "H"-scan for >the signatue checks on these new tubes. >What has been you experiences / recommendations ? > >Ian > >Trinidad and Tobago.