You should rename your variable to something else. id is already used for database records and incremented by default.

your_field = field.Integer(string="SST", default=lambda self: self.env['ir.sequence'].next_by_code('increment_your_field')

with : 

<record id="increment_your_field_sequence" model="ir.sequence">
    <field name="name">Field Incrementation</field>
    <field name="code">increment_your_field</field>
    <field name="prefix"></field>
    <field name="padding">3</field>
    <field name="company_id" eval="False"/>
</record>

Padding may be changed to a higher number, it's based on how records you may have ( in this case, you will get 001,002,003,004,005,006...999)