{"product_id":"zrn-anode","title":"ZRN Zinc Rod Anode — No Core","description":"\u003ch2\u003eZRN Zinc Rod Anode — No Core\u003c\/h2\u003e\n\u003cp\u003eSolid extruded, drawn or rolled zinc rod with no core, sized by nominal pipe size and supplied in 36 in or 72 in lengths. Cut to suit.\u003c\/p\u003e\n\u003cp\u003eZinc sacrificial anode to \u003cstrong\u003eMIL-DTL-18001L\u003c\/strong\u003e, type\n\u003cstrong\u003eZRN\u003c\/strong\u003e — rod, no core.\nSupplied in 5 sizes. Quoted on request.\u003c\/p\u003e\n\n\u003ch3\u003eSizes\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eType\u003c\/th\u003e\n\u003cth\u003eSize\u003c\/th\u003e\n\u003cth\u003eSpec figure\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eZRN-1\/8\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1\/8 nominal pipe size — 10.3 mm dia\u003c\/td\u003e\n\u003ctd\u003eFig 23\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eZRN-1\/4\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1\/4 nominal pipe size — 13.7 mm dia\u003c\/td\u003e\n\u003ctd\u003eFig 23\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eZRN-3\/8\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e3\/8 nominal pipe size — 17.1 mm dia\u003c\/td\u003e\n\u003ctd\u003eFig 23\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eZRN-1\/2\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e1\/2 nominal pipe size — 21.3 mm dia\u003c\/td\u003e\n\u003ctd\u003eFig 23\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eZRN-3\/4\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e3\/4 nominal pipe size — 26.7 mm dia\u003c\/td\u003e\n\u003ctd\u003eFig 23\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cp\u003e\u003cem\u003eFull dimensions, in inches and millimetres together, are on the\nspecification drawing in the images above — that drawing is the only place those\ndimensions exist in both units.\u003c\/em\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cem\u003eZRN-1\/8: 0.18 kg\/ft (0.40 lb\/ft) · ZRN-1\/4: 0.32 kg\/ft (0.71 lb\/ft) · ZRN-3\/8: 0.50 kg\/ft (1.10 lb\/ft) · ZRN-1\/2: 0.78 kg\/ft (1.71 lb\/ft) · ZRN-3\/4: 1.21 kg\/ft (2.67 lb\/ft)\u003c\/em\u003e\u003c\/p\u003e\n\n\n\u003ch3\u003eAlloy and water\u003c\/h3\u003e\n\u003cp\u003eMIL-DTL-18001L is a \u003cstrong\u003ezinc\u003c\/strong\u003e specification, supplied to\n\u003cstrong\u003eASTM B418 Type I\u003c\/strong\u003e — the alloyed seawater grade whose composition is\nwritten to meet MIL-A-18001K. That is why every supplier's datasheet claims to\n\"meet or exceed military specification\".\u003c\/p\u003e\n\u003cp\u003eFor \u003cstrong\u003efresh water\u003c\/strong\u003e zinc is the wrong alloy: use magnesium to\n\u003cstrong\u003eASTM B843\u003c\/strong\u003e, or zinc to \u003cstrong\u003eASTM B418 Type II\u003c\/strong\u003e, the\nhigh-purity grade for fresh and buried service. We cast to either — say which\nwater it is going into and we will quote the right one.\u003c\/p\u003e\n\n\u003ch3\u003eWhat to put on your purchase order\u003c\/h3\u003e\n\u003cp\u003eZinc anodes fail by \u003cstrong\u003epassivating\u003c\/strong\u003e: they skin over and stop\nproducing current while still looking perfectly serviceable. Iron contamination\nis the usual cause, which is exactly what ASTM B418 caps at 0.005%. Specify\n\u003cstrong\u003e\"to ASTM B418 Type I, mill certificate with each lot\"\u003c\/strong\u003e and you\nhave something to test against.\u003c\/p\u003e\n\n\u003ch3\u003eSizing\u003c\/h3\u003e\n\u003cp\u003eThe specification sets what the anode is, not how much of it you need. That\ncomes from \u003cstrong\u003eDNV-RP-B401\u003c\/strong\u003e for ships and offshore structures and\n\u003cstrong\u003eABYC E-2\u003c\/strong\u003e for boats. Whatever the calculation says,\n\u003cstrong\u003ereplace at about 50% wasted\u003c\/strong\u003e — output falls away as surface area\nis lost, so the last half protects far less than the first.\u003c\/p\u003e\n\n\u003ch3\u003eReading the type code\u003c\/h3\u003e\n\u003cp\u003eThese designations come from the military specification, not from any\nmanufacturer, which is why the same letters appear across every brand and why an\nold anode can nearly always be identified. Three letters: metal, then shape, then\ncore. \u003cstrong\u003eZ\u003c\/strong\u003e is zinc; \u003cstrong\u003eH\u003c\/strong\u003e hull slab,\n\u003cstrong\u003eS\u003c\/strong\u003e submarine slab, \u003cstrong\u003eT\u003c\/strong\u003e teardrop,\n\u003cstrong\u003eE\u003c\/strong\u003e fairwater slab, \u003cstrong\u003eR\u003c\/strong\u003e rod, \u003cstrong\u003eB\u003c\/strong\u003e bar,\n\u003cstrong\u003eD\u003c\/strong\u003e disc, \u003cstrong\u003eM\u003c\/strong\u003e mooring chain; then\n\u003cstrong\u003eS\u003c\/strong\u003e steel strap, \u003cstrong\u003eB\u003c\/strong\u003e brass straps,\n\u003cstrong\u003eC\u003c\/strong\u003e core strap, \u003cstrong\u003eP\u003c\/strong\u003e pipe core,\n\u003cstrong\u003eM\u003c\/strong\u003e interlocking core, \u003cstrong\u003eN\u003c\/strong\u003e no core.\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"\/collections\/anodes\"\u003eSee every MIL-DTL-18001 type we supply →\u003c\/a\u003e\u003c\/p\u003e","brand":"Dibblee","offers":[{"title":"1\/8 nominal pipe size — 10.3 mm dia","offer_id":50199393337621,"sku":null,"price":0.0,"currency_code":"USD","in_stock":true},{"title":"1\/4 nominal pipe size — 13.7 mm dia","offer_id":50199393370389,"sku":null,"price":0.0,"currency_code":"USD","in_stock":true},{"title":"3\/8 nominal pipe size — 17.1 mm dia","offer_id":50199393403157,"sku":null,"price":0.0,"currency_code":"USD","in_stock":true},{"title":"1\/2 nominal pipe size — 21.3 mm dia","offer_id":50199393435925,"sku":null,"price":0.0,"currency_code":"USD","in_stock":true},{"title":"3\/4 nominal pipe size — 26.7 mm dia","offer_id":50199393468693,"sku":null,"price":0.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0672\/4160\/7445\/files\/mil-zrn_48f008d6-37cc-4d1a-a829-057839fbc825.jpg?v=1790108014","url":"https:\/\/www.kentershackle.com\/products\/zrn-anode","provider":"Kenter Shackles","version":"1.0","type":"link"}