Petrochemical supply in Oman

The baseline transmission grade. X52 balances weldability against pressure rating, which is why it remains the default for gathering lines, utility piping and plant interconnects where wall thickness rather than yield strength drives the design.

Molybdenum-bearing austenitic stainless steel. The 2-3% Mo addition transforms pitting resistance in chloride-bearing media, making 316L the baseline grade for marine and chemical service in the Gulf.

Titanium and niobium stabilised austenitic grades. The stabilising addition ties up carbon so the steel resists intergranular corrosion after prolonged exposure in the 425-815 C sensitisation range.

Carbon pressure vessel plate for moderate and lower temperature service. The lower carbon of Grade 60 gives better formability and weldability than Grade 70, which suits cold-formed heads, thin shells and plant where notch toughness matters more than tensile strength.

High strength thermomechanically rolled line pipe for long distance, large diameter transmission. X70 is specified where the pipeline economics are driven by wall thickness and steel tonnage over hundreds of kilometres.

High alloy austenitic grade with 4-5% molybdenum and copper, bridging the gap between 316L and nickel alloys for sulphuric and phosphoric acid service.

The default carbon pressure vessel plate. Grade 70 carries the highest tensile of the SA516 family, and for sour service it is supplied with controlled sulphur, calcium treatment and HIC / SSC testing so wet H2S equipment can be built from a qualified plate rather than an upgrade alloy.

The high-temperature austenitic. 25Cr-20Ni gives scaling resistance to around 1035 C in continuous service, so 310S is the grade for furnace internals, radiant tubes and anything that lives in flue gas rather than in water.

A molybdenum-up step on 316L. Raising Mo to 3 - 4% lifts PREN to around 30, which buys real margin against pitting and crevice attack in pulp, scrubber and chloride service where 316L is borderline but duplex is more than the duty needs.

Titanium-stabilised 316. The titanium ties up carbon so the steel keeps its intergranular corrosion resistance after long exposure in the 425 - 815 C sensitisation range, and it holds higher creep strength than 316L in hot service.

The most widely used duplex grade. Roughly double the yield strength of 316L, allowing thinner and lighter sections while delivering far better chloride stress corrosion cracking resistance.

Nickel-chromium-molybdenum alloy strengthened by niobium. Exceptional strength and corrosion resistance from cryogenic temperatures to 980 C without heat treatment.

Commercially pure titanium, the industry workhorse. Fully resistant to seawater and oxidising chlorides with excellent formability and weldability.

Solid solution nickel-chromium-iron alloy with high resistance to oxidation, carburisation and chloride ion stress corrosion cracking at elevated temperature.

Nickel-copper alloy with outstanding resistance to flowing seawater, hydrofluoric acid and alkalis, and total immunity to chloride stress corrosion cracking.

Nickel-molybdenum-chromium alloy with tungsten, regarded as the most universally corrosion resistant alloy available for both oxidising and reducing media.

Iron-nickel-chromium alloy for high temperature strength with oxidation and carburisation resistance. The 32Ni-21Cr balance resists chloride stress corrosion cracking that austenitic stainless suffers, which is why it is standard for process heater and reformer tubing.

1.25Cr-0.5Mo-Si pressure vessel plate. The silicon addition improves oxidation resistance, making Grade 11 the common choice for hot wall vessels and hydrogen service up to around 550 C where full 2.25Cr strength is not required.

The creep-optimised version of Alloy 800. Controlled carbon plus a combined aluminium and titanium window of 0.85 - 1.20% gives far better creep rupture strength above 600 C, so 800HT is the grade for the hottest reformer and pigtail service rather than plain 800.

1Cr-0.5Mo pressure vessel plate. The economical Cr-Mo grade for moderate temperature pressure parts, widely used for separator and drum shells where creep and hydrogen resistance are needed but the duty is below the 2.25Cr range.

Nickel-iron-chromium with molybdenum, copper and titanium. The combination handles both reducing and oxidising acids and resists chloride stress corrosion cracking and sour well fluids, making 825 the standard CRA for sour service tubulars, cladding and acid plant.

2.25Cr-1Mo pressure vessel plate — the refinery standard for hydroprocessing. The higher chromium and molybdenum push the Nelson curve limit well above Grade 11, which is why reactors, separators and hot wall equipment in hydrogen service specify it.

Nickel-chromium-cobalt-molybdenum alloy for the extreme end of high temperature service. Solid solution strengthening keeps useful creep strength to 1100 C while the chromium and aluminium give oxidation resistance, so 617 is used where 800HT and stainless are long past their limit.

5Cr-0.5Mo plate. The chromium level lifts resistance to sulphidic corrosion and high temperature oxidation, so Grade 5 is specified for crude and vacuum unit hot sections where naphthenic and sulphur attack dominate.