Apparatus comprising furnaces, reactors or conduits used in applications requiring anti-coking properties and novel steel compositions

An apparatus comprising furnaces, reactors or conduits having at least internal walls composed at least partly of a steel comprising:

• 0 to 0.25% of C;
• 1.5% to 5% of Si;
• more than 7% to 10% of Cr;
• 0.5% to 2% of Mo;
• 0.3% to 1% of Mn;
• 0 to 0.03% of S;
• 0 to 0.03% of P;
• and
• the complement to 100% being essentially iron.

A steel comprising:

• at most 0.25% of C;
• more than 2.5% and up to 5% of Si;
• more than about 7% to 10% of Cr;
• 0.5% to 2% of Mo;
• 0.3% to 1% of Mn;
• at most 0.030% of S;
• and
• at most 0.03% of P:
• the complement to 100% being essentially iron.

An apparatus comprising furnaces, reactors or conduits having internal walls comprising at least partly of a steel consisting of:

• 0-0.25% of C;
• 1.5% to 5% of Si;
• above 7.1% to 10% of Cr;
• 0.5% to 2% of Mo;
• 0.3% to 1% of Mn;
• 0-0.03% of S;
• 0 to 0.03% of P;
• 0 to 0.1% of Nb;
• 0 to 0.40% of V;
• 0 to 10% of N;
• 0 to 0.05% of Al;
• 0 to 0.4% of Ni;
• and
• the compliment to 100% being iron.

A steel consisting essentially of:

• 0-0.25% of C:
• 2.5% to 5% of Si:
• above 7.1% to less than 10% of Cr:
• 0.5% to 2% of Mo:
• 0.3% to 1% of Mn:
• 0-0.03% of S:
• 0 to 0.03% of P:
• 0 to 0.1% of Nb:
• 0 to 0.40% of V:
• 0 to 0.10% of N:
• 0 to 0.05% of Al:
• 0 to 0.4% of Ni;
• and at most 0.2% of W
• the compliment to 100% being iron.