ميزة	شفة الفولاذ المقاوم للصدأ	Carbon Steel Flange
Main Alloy Elements	حديد, الكروم (≥10.5%), النيكل	حديد, الكربون (0.2–0.6%)
مقاومة التآكل	ممتاز	قليل (requires coating or lining)
Appearance	Silvery, bright, non-rusting	Dull gray, prone to rust
Magnetic Property	Usually non-magnetic (austenitic)	مغناطيسي
يكلف	أعلى	أدنى
Typical Grades	SS304, SS316, SS321	ASTM A105, A350 LF2, Q235

1. التفتيش البصري

الشفاه الفولاذ المقاوم للصدأ generally have a bright silver finish and resist oxidation. Even after extended exposure to air and moisture, they maintain a clean, shiny surface.

Carbon steel flanges, على الجانب الآخر, often appear dull gray or matte black. Without protective coatings like paint, الجلفنة, أو النفط, carbon steel flanges will rust over time.

Visual differences:

• الفولاذ المقاوم للصدأ: Polished or satin finish, clean look, no surface corrosion

• الصلب الكربوني: Dull, may have red/brown rust spots or black oxide coating

ساسا مستطيل supplies flanges with mill finish or custom surface treatment to ensure easy identification and superior corrosion protection.

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2. Magnet Test

This is a quick and easy field test to identify the general category of steel:

• الصلب الكربوني is always مغناطيسي

• الفولاذ المقاوم للصدأ varies:

  • Austenitic grades (على سبيل المثال, SS304, SS316): غير مغناطيسية or slightly magnetic

  • Ferritic and martensitic grades: مغناطيسي

Place a magnet on the flange. If it sticks strongly, it’s likely carbon steel or ferritic stainless. If it barely reacts or does not stick, it is likely austenitic stainless steel.

ملحوظة: Cold-working or machining austenitic stainless steel can make it slightly magnetic, so this test is not 100% conclusive.

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3. Spark Test

The spark test is commonly used in metal workshops:

• الصلب الكربوني produces طويل, branching orange sparks when touched with a grinder

• الفولاذ المقاوم للصدأ produces shorter, fewer sparks that are red or dull orange, often with less branching

This method requires experience and should be done with care. Always follow safety precautions when using grinders or spark tools.

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4. Weight Comparison

Stainless steel is slightly denser than carbon steel:

• Density of carbon steel: ~7.85 g/cm³

• Density of stainless steel (304/316): ~8.0 g/cm³

Although the difference is small, stainless steel flanges may feel slightly heavier than carbon steel flanges of the same size and design.

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5. Chemical Testing with Spot Kits

For more accuracy, chemical spot test kits are available to detect the presence of النيكل, الكروم, or molybdenum in stainless steel.

على سبيل المثال:

• حمض النيتريك: Stainless steel resists attack, while carbon steel shows rust or bubbling

• Copper sulfate: Reacts with carbon steel (copper plating visible) but not with stainless steel

These are semi-quantitative methods and give a reliable field indication of the material composition.

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6. Material Markings and Stamping

Reputable manufacturers like ساسا مستطيل mark each flange with:

• درجة المادة (على سبيل المثال, SS316, أ105)

• تصنيف الضغط (على سبيل المثال, 150#, 300#)

• Size and schedule

• معيار (على سبيل المثال, ASME B16.5)

• رقم الحرارة for traceability

Always check the stamping on the flange rim or hub. If a flange lacks clear markings, it should be tested before installation.

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7. تحديد المواد الإيجابية (مؤشر مديري المشتريات)

The most accurate way to distinguish flange material is اختبار مؤشر مديري المشتريات (PMI). using handheld analyzers like XRF (مضان الأشعة السينية) أو LIBS (laser-induced breakdown spectroscopy).

These devices provide:

• Elemental composition (على سبيل المثال, كر, في, الحديد, شهر)

• Grade matching (على سبيل المثال, confirms 316L vs 304)

• Instant results in the field or warehouse

PMI is often required for critical systems in زيت & غاز, أوعية الضغط, and food processing equipment.

ساسا مستطيل offers full PMI testing and certification for stainless steel and carbon steel flange deliveries upon request.

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8. Corrosion Behavior

Expose a small, cleaned section of the flange to salt water spray or a humid environment for 24–48 hours.

• الصلب الكربوني: Will show visible rust or reddish discoloration

• الفولاذ المقاوم للصدأ: Remains clean or may develop a light surface film, but no red rust

This simple exposure test helps confirm the corrosion resistance typical of stainless steel.

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Applications Based on Flange Material