There are two basic and chief Nickel compositions that are utilized in manufacturing nickel pipe –Nickel 200 and Nickel 201. Alloy 200 is a commercially pure wrought nickel alloy whilst alloy 201 is a low carbon version of alloy 200 that is used in applications where temperatures go high about 600of or 315oc. The low carbon % eliminates the production of grain boundary graphite phase that decreases ductility quickly. Nickel 200’s application is limited to the service temperature of 600of or 315oC. For applications at higher temperature, alloy 201 is preferred for use.

Pipes of both nickel grades are made in various diameters in schedules 5S, 10S, 40S and 80S. These are constructed in the following dimensions.

Pipe size, inch	Outer dia, inch	Schedule 5S		Schedule 10S
		Inner dia, inch	Wall thickness, inch	Inner dia, inch	Wall thickness, inch
1/8 in	0.405 in	–	–	0.31 in	0.05 in
¼ in	0.540 in	–	–	0.41 in	0.07 in
3/8 in	0.675 in	–	–	0.55 in	0.07 in
½ in	0.840 in	0.710 in	0.065 in	0.67 in	0.083 in
¾ in	1.050 in	0.920 in	0.065 in	0.88 in	0.083 in
1 in	1.315 in	1.185 in	0.065 in	1.09 in	0.11 in
1 ½ in	1.900 in	1.770 in	0.065 in	1.68 in	0.11 in
2 in	2.375 in	2.245 in	0.065 in	2.16 in	0.11 in
3 in	3.500 in	3.334 in	0.083 in	3.26 in	0.120 in
4 in	4.500 in	4.334 in	0.083 in	4.26 in	0.120 in
5 in	5.563 in	5.345 in	0.109 in	5.29 in	0.134 in
6 in	6.625 in	6.407 in	0.109 in	6.36 in	0.134 in
8 in	8.625 in	8.407 in	0.109 in	8.33 in	0.15 in
10 in	10.750 in	10.482 in	0.134 in	10.42 in	0.17 in
12 in	12.750 in	12.438 in	0.156 in	12.39 in	0.180 in
14 in	14 in	13.688 in	0.156 in	13.624 in	0.19 in
16 in	16 in	15.670 in	0.165 in	15.624 in	0.19 in
18 in	18 in	17.670 in	0.165 in	17.624 in	0.19 in
20 in	20 in	19.624 in	0.188 in	19.564 in	0.22 in
24 in	24 in	23.565 in	0.218 in	23.5 in	0.250 in
30 in	30 in	29.5 in	0.250 in	29.38 in	0.312 in

Fittings are offered in welding, threaded or flanged kinds. The fittings with long tangents are also offered for expanding. The recommended joining method for nickel pipe is by welding or expanding. While welding the nickel pipe, alloy 200 or alloy 201 filler metal and 131 and 141 electrodes are utilized.

Nickel pipe must be installed by following appropriate piping steps. No external stress needs to be sent to the pipe. The preferred maximum separations between the supports must be maintained which are based on insulated pipe transmitting liquid with a highest specific gravity of 1.35. The entire accessory items including valves, meters etc. must support independently to pipe or the support spacing should be limited. Flanges are utilized for connecting pipe to apparatus like vessels and pumps. Considering the cost, it is not suggested that flanges to be utilized for connecting pipe segments. The welding or expansion is the recommended procedure.

The excellent properties of nickel 200- outstanding resistance to caustic soda and other alkalis except ammonium hydroxide. Nickel 200 is not corroded by anhydrous ammonia or ammonium hydroxide in content of 1% or below. Higher contents can result in quick corrosion.

Nickel 200 provides outstanding resistance to the entire contents of caustic soda at temperatures about and including melting level. Lower than 50%, the attack rates are nominal. The valves and other essential equipments fitted in the pipe line need to be separately supported. It is also preferred that minimum one hanger must be used on every length of pipe, however allowed support spacing might be higher.

Monel 400 Pipes

Combining 30 to 33% copper with nickel, developing Monel 400, offers an alloy with several properties of chemically pure nickel however better than others. Dealing with water such as brackish and sea waters, is the chief application of Monel 400. It offers outstanding service in the high velocity media. The alloy can have pitting attack in the sluggish sea water as occurred to Nickel 200, but the corrosion rates are extremely small. The unavailability of chloride stress corrosion cracking is also an essential factor in choosing alloy 400.

Resistance to the general corrosion of alloy 400 in the non -oxidizing acids for example, sulfuric, hydrochloric and phosphoric is enhanced better than pure nickel. Alloy 400 is attacked in the oxidizing media including nitric acid, ferric chloride, chromic acid, wet chloride, sulfur dioxide or ammonia.

Nickel Monel 400 offers outstanding resistance to hydrofluoric acid media at the different contents and temperature limits. It is prone to stress corrosion cracking in wet, air saturated hydrofluoric or hydrofluosilicic acid vapor. However fracture occurs when it is fully plunged in the acid.

Attack on Alloy 400 is nominal in all kinds of application media

Interior conditions create a slight tarnish that is easily eliminated by wiping intermittently. Outer surfaces that are subjected to rain condition, create a thin grey green patina. In the sulfur based conditions, a soft, brown and reliable layer is produced.

Due to high nickel %, Monel 400 is resistant to caustic soda similar to Nickel, in the whole concentration limit. It also offers resistance to anhydrous ammonia and ammonium hydroxide solutions of about 3% content.

Maximum permitted design stress for Monel 400 Pipe

Temperature		Permitted design stress,
oF	oC
100	38	17.5 x 10(3) psi	16.6 x 10(3) psi
200	93	16.5 x 10(3) psi	14.6 x 10(3) psi
300	149	15.5 x 10(3) psi	13.6 x 10(3) psi
400	204	14.8 x 10(3) psi	13.2 x 10(3) psi
500	260	14.7 x 10(3) psi	13.1 x 10(3) psi
600	316	14.7 x 10(3) psi	13.1 x 10(3) psi
700	371	14.7 x 10(3) psi	13.1 x 10(3) psi
800	427	14.5 x 10(3) psi	13.1 x 10(3) psi
900	482	8 x 10(3) psi	8 x 10(3) psi

 Highest allowable operating pressure

Highest permitted application pressure
Pipe size, inch	100 of/ 38 oC	200 of /93 oC	300 of /149 oC	400 of /204 oC	700 of /371 oC	800 of /427 oC	900 of /482 oC
½ in	2462 psi	2362 psi	2219 psi	2118 psi	2104 psi	2075 psi	1145 psi
2/4 in	1947 psi	1868 psi	1755 psi	1675 psi	1664 psi	1641 psi	905 psi
1 in	1541 psi	1478 psi	1388 psi	1326 psi	1317 psi	1299 psi	716 psi
1 ½ in	1055 psi	1012 psi	950 psi	907 psi	901 psi	889 psi	490 psi
2 in	839 psi	805 psi	756 psi	722 psi	717 psi	708 psi	390 psi
3 in	725 psi	696 psi	654 psi	624 psi	620 psi	611 psi	337 psi
4 in	562 psi	539 psi	506 psi	483 psi	480 psi	474 psi	261 psi
5 in	578 psi	508 psi	473 psi	459 psi	456 psi	456 psi	261 psi
6 in	483 psi	425 psi	396 psi	384 psi	381 psi	381 psi	233 psi
8 in	370 psi	325 psi	303 psi	294 psi	292 psi	292 psi	178 psi
10 in	365 psi	321 psi	299 psi	290 psi	288 psi	288 psi	176 psi
12 in	358 psi	315 psi	296 psi	285 psi	282 psi	282 psi	172 psi

 Inconel alloy 600 Pipe

Alloy 600, a nickel –chromium- iron alloy is for service in conditions needing heat and corrosion resistance. The presence of high nickel percentage makes alloy 600 resistant to corrosion in the several organic and inorganic compounds and offers outstanding resistance to chloride ion stress corrosion cracking. The chromium % offers resistance to sulfur media and diverse oxidizing conditions.

Moreover, Inconel 600 offers outstanding mechanical characteristics, high strength and suitable workability. It functions suitably in the applications at temperatures varying from cryogenic to 1200of or 649oC.

Nickel alloy 600 cold drawn and annealed pipe is fabricated in schedules 5S, 10S, 40S, 80S and 160S.

Inconel 600 pipe is joined by welding or threading. The flanges are also offered however for use in connection to system or for spool components that may need to be removed regularly to clean. The recommended connection method is welding. Forged 600 alloy flanges as per USAS B16.5 steel flanges have various pressure temperature ratings as compare to the related basic functional ratings of equivalent steel flanges.

Proven piping methods must be followed while installing Inconel 600 pipe. Pipe must be carefully lined to confirm that configuration is stress free. In case the stress exists, corrosion resistance of 600 pipe will be widely affected. Sufficient support for pipe should also be given. The entire valves, apparatus or other components must be installed in the manner that should be separately supported. However significantly long spans are allowed, it is often beneficial to configure minimum single pipe support in each length of pipe.

Inconel 600 is fully resistant to corrosion in fresh waters and natural waters comprising of free carbon dioxide, iron compounds and dissolved air. It is resistant to SCC in boiling magnesium chloride. Due to its chromium %, Inconel 600 offers outstanding resistance to sulfuric acid (H2SO4) in the oxidizing media better than nickel 200 or Monel 400. The inclusion of oxidizing salts to H2SO4 passivate Inconel 600 that makes it fit for application in acid mine waters or brass pickling solutions, where Monel 400 is not suitable for use.

Alloy 600 is susceptible to SCC in the chloride salts however offers outstanding resistance in the whole non-oxidizing halides.

Inconel 625 Pipe

 Alloy 625 is a NiCrMoNb alloy most suitable for services that need strength and corrosion resistance. It offers great fatigue strength, high strength and hardness at temperatures varying from cryogenic limits to 2000of or 1093oC.

Inconel 625 inhiibts oxidation, general corrosion, pitting and crevice corrosion and is resistant to chloride stress corrosion cracking. These features are offered by inclusion of molybdenum and niobium (or columbium) to the basic Ni-Cr chemistry.

Prevention of attack in aqueous solutions is suitable for diverse applications such as in organic acids, sulfuric acids and hydrochloric acid at temperature limits below 150of or 65oC. Alloy 625 offers suitable resistance to hydrofluoric acid. However Nickel based super alloys are not commonly utilized in nitric acid application due to expensiveness, Inconel 625 is resistant to solutions of nitric-hydrofluoric, in which stainless steels lose their resistance capability.

Alloy 625 offers great resistance to phosphoric acid solutions, involving commercial acid types containing fluorides, sulfates and chlorides in the formation of super phosphoric acid containing 72 % P2O5. Normally, alloy 625 is chosen for applications where alloy 600 is not fit for use.

Incoloy 800 Pipe

Incoloy 800 comprises of 20 % chromium, 32 % nickel and 46% iron, it is commonly used for offering oxidation resistance and strength at the high temperatures. It is specifically useful for the elevated temperature services as it doesn’t create the embrittling sigma phase after prolong exposure at 1200of to 1600of or 649oC to 871oC. Large creep and rupture strengths are other factors that add to its functionality in the diverse applications.

Cold drawn seamless Incoloy 800 pipe is delivered in the annealed and pickled condition in schedules 4S, 10S, 40S and 80S.

Incoloy 800 pipe is recommended to be joined by welding. Inconel filler metal 82 is utilized for root pass and joining.

Considering the piping systems, standard piping guidelines must be followed. The whole pipes should be aligned carefully to prevent development of installation stress into pipes that will cause corrosion and may offer early damage of the system. The accessory items configured in line including valves and meters are separately supported. However prolong periods between supports are allowed, it is a suitable piping instruction to install a support on individual pipe length.

At the medium temperatures, alloy 800 offers similar resistance to general corrosion as of austenitic nickel-iron-chromium alloys. Although with increase in temperature, Incoloy 800 offers better corrosion resistance whilst austenitic steels become unsuitable for the application.

Incoloy 800 offers great resistance to nitric acid at content about 70%. It prevents attack in the diverse oxidizing salts however not in halide salts. It also offers great resistance in organic acids like formic, acetic and propionic. It is specifically fit for use in the hot corrosive gas media for example, hydrogen sulfide.

In aqueous corrosion application of alloy 800, it offers resistance between 304SS and 316SS hence it cannot be broadly used in the aqueous applications. It is resistant to stress corrosion cracking however not unaffected but superior than stainless steel 300 series.

Alloy 825 Pipe

Incoloy 825 is almost equivalent to alloy 800, although, the chemistry has been improved to offer enhanced aqueous corrosion resistance. Larger nickel content of alloy 825 that in Incoloy 800, makes it resistant to chloride ion stress corrosion cracking. Inclusion of molybdenum and copper offer resistance to pitting and crevice corrosion in reducing acid conditions for example sulfuric or phosphoric acid solutions. Incoloy 825 prevents attack in pure sulfuric acid mixtures about 40% by weight at boiling points and at all contents at the highest temperature of 150of or 60oC.

Hastelloy B-2 Pipe

Alloy B-2 is also resistant to several non-oxidizing chloride based salts for example aluminum chloride, magnesium chloride and antimony chloride. Alloy B2 contains nickel about 70%, it is resistant to chloride based stress corrosion cracking. With the presence of high molybdenum content, it is extremely resistant to pitting corrosion in acid chloride media.

Hastelloy B2 is not suggested for high temperature applications. Hastelloy pipes are limited to use in the application temperature up to 650of or 343oC. The chief factor that limits its use is the high sensitivity to corrosion in the oxidizing media. It is not resistant to oxidizing acids for example nitric and chromic or to oxidizing salts for example ferric chloride or cupric chloride. The availability of oxidizing salts in the reducing acids should be taken into account. The oxidizing salts- ferric chloride, ferric sulfate or cupric chloride in fact in ppm content %, increase the corrosion rate in HCl or H2SO4 acids. In other case dissolved oxygen has adequate oxidizing potential to influence the corrosion rates in HCl acid.

Hastelloy C-276 Pipe

Hastelloy C276 is a Nickel –Molybdenum- Chromium – Tungsten alloy offering great corrosion resistance that is also sustained in the welded form. The high percentages of nickel and molybdenum offer sufficient corrosion resistance in the reducing conditions, additionally the chromium% offers resistance to oxidizing agents. Molybdenum also increases resistance to localized corrosion in the heat affected zones of welded joints. Alloy C276 also offers good strength at room and high temperatures.

Hastelloy C-276 pipe is made in 5S, 10S, 40S and 80S. Pipes are seamless. Any corrosion chance is strictly prohibited. The pipes are joined by welding, threading or flanging. Considering the cost, flanging is not used broadly and only used for joining to pumps or other apparatus. Welding is the most preferred method for connecting pipes.

The installation procedure for Hastelloy C276 pipes should be conducted with utmost care to prevent any stress on the pipe system. The pipes should be completely aligned and supports must be given.

Titanium Pipes

Titanium is found as the 9th most abundantly available element on earth’s crust. However long ago identified as a lightweight, high strength and corrosion resistant element, titanium is comparatively a new element as compare to copper and nickel from the industrial point of view.

The production process of Titanium was developed in 18th century. Although it has been in the industry since 50 years because of the efforts of United States Bureau of Mines that the procedure has been enhanced adequately to achieve titanium in the commercial quantity.

The industrial use of titanium is due to its outstanding corrosion resistance and strength. It is produced in the four grades. Titanium metal is described as grade 2 that is mostly utilized for its corrosion resistance ability. It is light weight and has density little higher than iron or copper based alloys. Its elastic modulus is almost half of the steel. Specific heat and thermal conductivities are equivalent to stainless steel. It has small coefficient of thermal expansion.

Titanium pipe is produced in 5S, 10S, 40S and 80S.

Maximum allowable stress for titanium pipe is described as following:

Temperature		Highest permitted stress
100 of	38 oC	10,600 psi
150 of	66 oC	10,200 psi
200 of	93 oC	9300 psi
250 of	121 oC	8400 psi
300 of	149 oC	7700 psi
350 of	177 oC	7100 psi
400 of	204 oC	6500 psi
450 of	232 oC	6100 psi
500 of	260 oC	5600 psi
550 of	288 oC	5300 psi
600 of	316 oC	4800 psi

No chance for concentrated loads. The valves or accessories installed in the pipe line should be supported independently. In case of using carbon steel hangers, they must be padded to avoid them contacting the titanium pipe to eliminate the chance of galvanic corrosion. In such condition, only carbon steel hanger will be attacked that would ultimately fail in supporting the pipe.

The corrosion resistance properties of Titanium are because of production of stable, secured and strongly adherent oxide layer that covers its outer surface. The layer is produced instantly when a new surface comes in contact of air and humidity. The oxide layer on the metal is thin but it is extremely reliable and is only damaged by some materials such as hydrofluoric acid. Due to its strong affinity for oxygen, titanium has excellent recovery attributes that its layer is renewed instantly in any condition where it finds moisture or oxygen. Hence, we note that titanium is isolated from attack of wet chlorine gas. If the wet % of dry chlorine gas is below 0.5 %, quick or even intense corrosion may occur.

Titanium should not be used in dry conditions without oxygen because the security layer may not be reproduced if depleted.

Titanium is isolated from all kinds of corrosions in marine water and chloride salt solutions at the very low temperatures. In the specific conditions of chloride solutions, the metal is susceptible to pitting and crevice corrosion. The temperature at which the corrosion is noticed is based on the pH value of mixture. If pH value is above 7.8, general corrosion occurs at 300of or 149oC.

Titanium provides outstanding resistance to oxidizing acids like nitric and chromic. It has controlled resistance to reducing acids for example, hydrochloric, sulfuric and phosphoric acid.