On­site por­ta­ble XRD cor­ro­sion anal­y­sis

DEMM Engineering & Manufacturing - - COATINGS & CORROSION CONTROL -

The eco­nomic i mpact of all types of cor­ro­sion and its degra­da­tion of in­fra­struc­ture, such as pipe­lines, oil rigs and tow­ers, rep­re­sents an an­nual cost of many bil­lions of dol­lars to in­dus­try. In a 2016 re­port is­sued by NACE (USA) this was es­ti­mated to be more than three per­cent of an­nual global GDP. In ad­di­tion to be­ing an eco­nomic threat to in­dus­try and the wider com­mu­nity, cor­ro­sion can also be a phys­i­cal threat to in­fra­struc­ture and the safety of staff and mem­bers of the public.

Ef­fec­tive cor­ro­sion man­age­ment strate­gies can help re­duce the cost. A key part of such a pro­gram is the rapid iden­ti­fi­ca­tion of the cor­ro­sion and scal­ing prod­ucts so that the ap­pro­pri­ate con­trols are im­ple­mented. For re­mote min­ing op­er­a­tions or off-shore oil pro­duc­tion fa­cil­i­ties, the cost of test­ing any sort of sam­ple is in­creased by the need to trans­port it to a spe­cial­ist lab­o­ra­tory. Even within ma­jor cities and re­gional cen­tres it can of­ten take weeks for lab­o­ra­to­ries to an­a­lyse sam­ples.

There are also in­tan­gi­ble costs that can have a sig­nif­i­cant im­pact upon busi­nesses and the wider com­mu­nity. Any dis­rup­tion to pro­duc­tion at an oil re­fin­ery or steel man­u­fac­tur­ing plant can cost hun­dreds of thou­sands of dol­lars or more – in any cur­rency - each day.

One anal­y­sis tech­nique that can be used in cor­ro­sion man­age­ment is X-ray dif­frac­tion ( XRD). Ac­cord­ing to Dane Bur­kett, Prod­uct Spe­cial­ist with Olym­pus, “Tra­di­tional anal­y­sis of cor­ro­sion prod­ucts only in­di­cates their pres­ence, or their chem­i­cal com­po­si­tion, such as iron (Fe) -bear­ing cor­ro­sion. XRD can iden­tify and quan­tify cor­ro­sion and scal­ing prod­ucts – for ex­am­ple mag­netite or ak­a­ganeite – by char­ac­ter­is­ing their crys­tal­lo­graphic struc­ture.” A ge­ol­o­gist by train­ing, Bur­kett’s role in­volves meet­ing with clients to de­ter­mine their anal­y­sis re­quire­ments, in ad­di­tion to ap­pli­ca­tion sup­port.

To en­sure ef­fi­cient and pro­duc­tive use of a min­ing or pro­duc­tion as­set, a cor­ro­sion en­gi­neer or chemist needs the anal­y­sis in­for­ma­tion fast so they can

best iden­tify the cor­ro­sion prod­ucts and plan and im­ple­ment re­pair and main­te­nance strate­gies ac­cord­ingly.

The time taken to get a sam­ple from an off­shore as­set to a lab with XRD ca­pa­bil­i­ties can take weeks and cost a com­pany thou­sands of dol­lars, in ad­di­tion to the cost of the down­time of their as­set.

How­ever, com­pre­hen­sive com­po­si­tional ma­te­ri­als anal­y­sis can now be car­ried out on­site us­ing the field por­ta­ble Terra XRD and XRF anal­yser from Olym­pus. “Us­ing a Terra unit, our cus­tomers can an­a­lyse their sam­ples di­rectly on an oil plat­form, re­mote plant or re­fin­ery,” Bur­kett said. “The re­sults can then be trans­mit­ted back to a cor­ro­sion ex­pert – either on or off-site – to help de­vise a so­lu­tion.”

The crys­tal­lo­graphic struc­ture of cor­ro­sion and scal­ing prod­ucts is unique, much like a fin­ger­print, and XRD is used to de­fine this char­ac­ter­is­tic struc­ture. XRD works by sub­ject­ing a sam­ple to a monochro­matic X-ray beam and mea­sur­ing the an­gles at which the X-rays dif­fract. A com­bi­na­tion of dif­frac­tion an­gles is char­ac­ter­is­tic of a given phase of a par­tic­u­lar cor­ro­sion or scal­ing prod­uct.

Un­like other meth­ods – such as in­fra-red spec­troscopy – which iden­tify com­pounds, XRD can iden­tify and quan­tify all crys­talline phases, ir­re­spec­tive of re­flectance. (Opaque phases such as mag­netite can­not be iden­ti­fied us­ing in­fra-red spec­troscopy.)

In ad­di­tion, XRD can dis­tin­guish be­tween dif­fer­ent cor­ro­sion and scal­ing prod­ucts that have the same, or sim­i­lar chem­istry. For ex­am­ple, the fer­rous cor­ro­sion prod­ucts goethite, lep­i­docrocite, fer­ox­y­hyte and ak­a­ganeite can be dis­tin­guished from each other, even though they all have the chem­i­cal for­mula FeO(OH).

The iden­ti­fi­ca­tion of com­pounds (as op­posed to ele­men­tal com­po­si­tions) is cru­cial for the un­der­stand­ing of cor­ro­sion pro­cesses. “Dif­fer­ent cor­ro­sion and scal­ing prod­ucts form un­der dif­fer­ent con­di­tions and in dif­fer­ent en­vi­ron­ments,” said Bur­kett. “In­for­ma­tion about the pres­ence and quan­tity of these phases is not only help­ful in ex­plain­ing the cor­ro­sion process, but can help to de­ter­mine the root cause, lo­cate the ori­gin of cor­ro­sion in a fa­cil­ity and, at the same time, in­di­cate pos­si­ble so­lu­tions to the prob­lem.”

Once a cor­ro­sion or scal­ing prod­uct is iden­ti­fied, it is pos­si­ble to de­ter­mine the tem­per­a­ture, pres­sure, fluid chem­istry and pH con­di­tions un­der which it formed. “If you know what it is then you can de­ter­mine the best way to treat it,” Bur­kett added. “This might be with an acid wash or adding some type of in­hibitors into the process.” Other treat­ments in­clude use of, bac­te­ri­cides, al­ter­na­tive or en­hanced coat­ings, milling the in­side of the ma­chin­ery or, ul­ti­mately, re­place­ment of the equip­ment.

Know­ing how cor­ro­sion prod­ucts form al­lows an en­gi­neer to op­ti­mise a process to stop or slow their oc­cur­rence. For ex­am­ple, the tem­per­a­ture or pres­sure pa­ram­e­ters can be ad­justed or leaks can be lo­cated and re­paired.

Olym­pus cus­tomers are us­ing the com­pany’s in­stru­ments for rou­tine anal­y­sis of cor­ro­sion ma­te­rial found at re­finer­ies, pipe­lines, off­shore oil plat­forms, coal fire power gen­er­a­tion plants and geo­ther­mal plants and drilling sites.

“The ap­pli­ca­tion of our in­stru­ments to cor­ro­sion and scal­ing are many and var­ied,” Bur­kett stated. “Our in­stru­ments are be­ing used for root cause anal­y­sis of per­sis­tent cor­ro­sion by in­spec­tion com­pa­nies, through to restora­tion of his­tor­i­cal and ar­chae­o­log­i­cal arte­facts by mu­se­ums and uni­ver­si­ties.

“Cor­ro­sion anal­y­sis is an ex­cit­ing ap­pli­ca­tion for us,” Bur­kett added. “Be­ing able to con­duct analy­ses on site with a trans­portable unit that can be de­ployed to site can make im­mense cost sav­ings.”

The Terra por­ta­ble XRD anal­yser is a high per­for­mance, self- con­tained, bat­tery op­er­ated, closed-beam XRD sys­tem that pro­vides full phase iden­ti­fi­ca­tion of ma­jor, mi­nor and trace com­po­nents. The ruggedised and func­tional unit com­bines X-ray Dif­frac­tion and qual­i­ta­tive X-ray Flu­o­res­cence ( XRF) anal­y­sis in a sin­gle in­stru­ment. The Terra de­liv­ers sav­ings in op­er­a­tional

Know­ing how cor­ro­sion prod­ucts form al­lows an en­gi­neer to op­ti­mise a process to stop or slow their oc­cur­rence.

costs, space, and time along with seam­less in­te­gra­tion of data and re­sults. The sam­ple prepa­ra­tion and op­er­a­tion of the anal­yser do not re­quire de­tailed tech­ni­cal knowl­edge so any­one on­site can run the test.

OUT OF THIS WORLD TECH­NOL­OGY

The tech­nol­ogy in­side the Olym­pus Terra was ini­tially con­ceived to per­form chem­i­cal and min­er­alog­i­cal test­ing for NASA’s Mars Sci­ence Lab­o­ra­tory (MSL) mis­sion. Com­bin­ing both Olym­pus and NASA in­no­va­tion, the Terra en­ables a new way of per­form­ing XRD and XRF mea­sure­ments as part of Earth­bound ap­pli­ca­tions.

Us­ing a specif­i­cally de­vel­oped di­rect ex­ci­ta­tion charge cou­pled de­vice (CCD) ‘cam­era’, Terra is able to col­lect X-ray pho­ton data for both X-ray dif­frac­tion and X-ray flu­o­res­cence si­mul­ta­ne­ously. The cam­era has the abil­ity to de­tect both pho­ton po­si­tion and pho­ton en­ergy at the same time. In sim­ple terms, the Terra can si­mul­ta­ne­ously mea­sure XRD for quan­ti­fy­ing cor­ro­sion prod­ucts and XRF for qual­i­ta­tive chem­istry. With en­ergy res­o­lu­tion of ~200 eV (5.9 keV), Terra makes XRF anal­y­sis as sim­ple as view­ing the soft­ware spec­trum dis­play.

The Terra sim­pli­fies sam­ple prepa­ra­tion and load­ing for X-ray dif­frac­tion ex­per­i­ments. The prepa­ra­tion, load­ing and un­load­ing of sam­ples is so easy, that a tech­ni­cian can be trained to load a sam­ple within a mat­ter of sec­onds. To en­sure a suf­fi­ciently ran­dom ori­en­ta­tion of crys­tals, the patented sam­ple vi­bra­tion cham­ber built into the Terra elim­i­nates the re­quire­ment to finely grind – grains < 10 μm – and press the sam­ple into a pel­let. Re­quir­ing a mere 15 mg sam­ple at < 150 μm, the vi­bra­tion cham­ber’s con­vec­tion process presents the in­stru­ment op­tics with mul­ti­ple ori­en­ta­tions of the crys­talline struc­ture. The re­sult­ing X-ray dif­frac­tion pat­tern is vir­tu­ally free of ‘pre­ferred- ori­en­ta­tion ef­fects’ of­ten en­coun­tered when us­ing con­ven­tional, lab-based XRD in­stru­ments.

The Terra’s unique pow­der­han­dling sys­tem, non-me­chan­i­cal go­niome­ters – used to mea­sure an­gles – and lack of com­pli­cated mov­ing parts, makes it ideal for those ap­pli­ca­tions where field porta­bil­ity and ease of use are im­por­tant.

Olym­pus be­lieves it can hold its place at the fore­front of the devel­op­ment of X-ray anal­y­sis tech­nol­ogy which pro­vides fast, non- de­struc­tive qual­i­ta­tive and quan­ti­ta­tive char­ac­ter­i­sa­tion of ma­te­ri­als. In­stru­ments de­vel­oped by Olym­pus can be used for de­tec­tion, iden­ti­fi­ca­tion and anal­y­sis of el­e­ments at a range of con­cen­tra­tions.

The Terra can be used in a wide range of ap­pli­ca­tions in­clud­ing oil/gas, geo­ther­mal and min­eral ex­plo­ration; min­eral pro­cess­ing; min­eral iden­ti­fi­ca­tion; mid- stream pro­cess­ing for phar­ma­ceu­ti­cals and in­dus­trial ma­te­ri­als; coun­ter­feit drug screen­ing; fire and ex­plo­sives foren­sics; and cor­ro­sion mon­i­tor­ing.

Olym­pus says its devel­op­ment engi­neers con­tin­u­ally in­ves­ti­gate dif­fer­ent de­tec­tors, fil­ter­ing tech­niques and anal­y­sis al­go­rithms to im­prove the sen­si­tiv­ity and ac­cu­racy of its X- ray anal­y­sis sys­tems. To­day, the Terra unit pro­vides the ad­van­tages of large lab­o­ra­tory based XRD and XRF test­ing in a fast, por­ta­ble and cost- ef­fec­tive unit.

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