إجابات مباشرة
إجابات على الأسئلة التي يطرحها المشترون فعلياً
أسئلة المواصفات والشراء مُجابة من المعايير ومن المخزون المتوفر لدينا في دبي — بلا تسويق، فقط التفاصيل العملية التي تحتاجها قبل إرسال طلبك.
Grade selection
What is the difference between 304 and 316 stainless steel?316 stainless steel contains 2 to 3% molybdenum and 304 contains none. That molybdenum is what resists chloride pitting, so 316 is used in seawater, brine and coastal plant while 304 is used in dry, fresh-water and food duty. Both are austenitic, weldable and non-magnetic in the annealed condition.What is the pipe equivalent of SA387 Grade 22 plate?A335 P22 is the seamless pipe equivalent of SA387 Grade 22 Class 2 plate. Both are 2.25Cr-1Mo, normalised and tempered, for elevated temperature and hydrogen service. The matching fittings are A234 WP22 and the matching flanges are A182 F22, so a complete 2.25Cr-1Mo circuit can be built from one chemistry.When should I use Inconel 625 instead of Incoloy 825?Alloy 825 is an iron-nickel-chromium alloy with copper and molybdenum, chosen for sulphuric and phosphoric acid and for sour service economy. Alloy 625 is a true nickel-chromium-molybdenum-niobium alloy with far higher strength and chloride resistance, used for seawater, hot gas and high temperature strength above 600 C.Can I use S355 structural plate for a pressure vessel instead of SA516 Grade 70?No. SA516 Grade 70 is a pressure vessel plate qualified under ASME Section II with controlled chemistry, fine grain practice and impact testing, and it is what ASME Section VIII allows. S355J2+N is a structural grade to EN 10025-2 — suitable for frames, skids and supports, not for a coded pressure boundary.Should I use 90/10 or 70/30 cupro nickel for seawater piping?90/10 (C70600) is the default for seawater piping and firewater systems up to about 2.4 m/s flow velocity. 70/30 (C71500) carries more nickel, higher strength and greater resistance to impingement and erosion, so it is specified for higher velocity lines, condenser tubing and hotter brine duty.What is the difference between titanium Grade 2 and Grade 5?Grade 2 is unalloyed commercially pure titanium — formable, weldable and chosen for corrosion resistance in seawater, chlorides and oxidising acids. Grade 5 (Ti-6Al-4V) is an alpha-beta alloy with roughly three times the strength, used where load and weight matter, but it is less formable and more demanding to weld.Should I specify 4140 or 4340 for a shaft?4140 (42CrMo4) is the default engineering steel for shafts, gears and couplings up to roughly 100 mm diameter. 4340 (34CrNiMo6) adds about 1.8% nickel, which carries hardenability and toughness deep into large sections, so it is the choice above about 100 mm or where impact toughness governs.What is the difference between Armox 500T and Armox 600T?Armox 500T is around 480 to 540 HBW and remains workable — it can be cut, bent and welded by a competent fabricator, which is why it covers most vehicle and architectural protection. Armox 600T is around 570 to 640 HBW, stops higher threat levels at lower weight, but is far less forgiving to form and weld.
Certification
What does an EN 10204 3.1 certificate mean?EN 10204 3.1 is a mill test certificate of specific test results, validated by the manufacturer's own inspection department, which must be independent of the production department. It reports the actual heat chemistry and mechanical test results for the material supplied, traceable by heat number — not typical values.What is the difference between API 5L PSL1 and PSL2?PSL2 is the stricter product specification level. It adds mandatory limits on carbon equivalent, tighter sulphur and phosphorus, a maximum as well as minimum yield strength, a yield-to-tensile ratio cap and compulsory Charpy impact testing. PSL1 has none of those requirements. Pipeline projects almost always specify PSL2.What does NACE MR0175 / ISO 15156 compliance actually require?It requires that the material, its hardness, its heat treatment condition and its cold work level are all qualified for the specific partial pressure of H2S, chloride content, pH and temperature of your service. It is a service-specific qualification with documented hardness limits, not a grade label a mill can simply stamp on.
Fabrication
Is Hardox 450 weldable, and does it need preheat?Yes. Abrasion resistant plate in the 450 HBW class is readily weldable with standard low-hydrogen consumables because the carbon equivalent is kept low. Plate up to about 20 mm usually needs no preheat above 20 C; thicker sections, restrained joints or cold workshops call for 75 to 100 C preheat.When does UHMW-PE lining beat a steel wear liner?UHMW-PE wins where material is sticking, bridging or freezing rather than abrading — coal and damp ore chutes, bins and hoppers. Its low friction keeps flow moving and it weighs an eighth of steel. Abrasion resistant steel still wins on high impact, sharp rock and temperatures above about 80 C.What is a BA finish tube and when is it required?BA means bright annealed: the tube is annealed in a controlled reducing atmosphere so it leaves the furnace with a clean, bright, scale-free surface needing no pickling. It is specified where surface cleanliness and low roughness matter — pharmaceutical, food, semiconductor and high purity gas and instrument lines.